TESTING  MILK 

AND  ITS  PRODUCTS 


FARRINGTON  AND  WOLL 


This  book  is  DUE  on  the  last  date  stamped  below. 

JJL*   193V 


FEB   1     1924 
APR  7     1926 

MAY  14 

NOV  1 5   1929 
OCT  1  5  193C 


1951 


28 


^211947 


DEC1819 


DR.  S.  M.  BABCOCK 
Inventor  of  the  Babcock  Milk  Test 


TESTING  MILK 

AND  ITS  PRODUCTS 


A  MANUAL  FOR  DAIRY  STUDENTS,  CREAMERY  AND 

CHEESE  FACTORY  OPERATORS,  FOOD  CHEMISTS 

AND  DAIRY  FARMERS 


BY 
( 


E.  H.  FARRINGTON       and          F.  W.  WOLL 

Profettor  in  Charge. of  Dairy  School  Profeisor  of  Animal  Nutritic 

UNIVERSITY  OF  WISCONSIN  UNIVERSITY  OF  CALIFORNIA 


With  Illustrations 


TWENTY  FOURTH  REVISED  AND  ENLARGED  EDITION 


MADISON,  WIS. 

MENDOTA  BOOK  COMPANY 


ALL   RIGHTS   RESERVED 


COPYRIGHT,  1897,  1899,  1901,  1904,  1909,  1911,  1913,  AND  1918 
BY  E.  H    FARRINGTON  AND  F.  W.  WOLL 


CANTWELL    PRINTING    COMPANY 
MADISON,    WIS. 


PREFACE  TO  FIRST  EDITION. 


The  present  volume  is  intended  for  the  use  of  dairy  students, 
factory  operators,  dairymen,  food  chemists,  and  others  interested 
in  the  testing  or  analysis  of  milk  and  its  products.  The  subject 
has  been  largely  treated  in  a  popular  manner;  accuracy  and 
clearness  of  statement,  and  systematic  arrangement  of  the  sub- 
ject  matter  have,  however,  been  constantly  kept  in  mind.  The 
aim  has  been  to  make  the  presentation  intelligible  to  students 
with  no  further  training  than  a  common-school  education,  but 
their  work  will  naturally  be  greatly  lightened  by  the  aid  of  an 
able  teacher. 

Complete  directions  for  making  tests  of  milk  and  other  dairy 
products  are  givem;  difficulties  which  the  beginner  may  meet 
with  are  considered  in  detail,  and  suggestions  offered  for  avoid- 
ing  them.  It  is  expected  that  a  factory  operator  or  practical 
dairyman,  by  exercising  common  sense  and  ordinary  care,  can 
obtain  sufficient  knowledge  of  the  subject  through  a  study  of 
the  various  chapters  of  this  book  to  make  tests  of  milk,  cream, 
etc.,  even  if  be  has  had  no  previous  experience  in  this  line. 

For  the  benefit  of  advanced  dairy  students  who  are  somewhat 
familiar  with  chemistry  and  chemical  operations,  Chapter  XIV 
has  been  added  giving  detailed  instructions  for  the  complete 
chemical  analysis  of  milk  and  other  dairy  products.  The  detee- 
tion  of  preservatives  and  of  artificial  butter  or  filled  cheese  has 
also  been  treated  in  this  connection. 

As  the  subject  of  milk  testing  is  intimately  connected  with 
the  payment  for  the  milk  delivered  at  butter-  and  cheese  fac 
tories,  and  with  factory  dividends,  a  chapter  has  been  devoted 
to  a  discussion  of  the  various  systems  of  factory  book-keeping, 
and  tables  greatly  facilitating  the  work  of  the  factory  secretary 
or  bookkeeper  have  been  prepared  and  are  included  in  the 
Appendix. 

Madison,   Wis.,  October   1,   1897. 


PREFACE  TO  REVISED  EDITION. 


Each  year  that  passes  brings  some  valuable  contributions  to  our 
knowledge  of  the  subjects  treated  in  this  book  and  a  frequent  re- 
vision of  it  is  therefore  desirable.  The  present  edition  contains 
descriptions  of  methods  and  apparatus  that  have  stood  the  test  of 
actual  use  during  the  past  few  years;  the  new  information  pub- 
lished since  the  last  revision  of  the  book  has  been  carefully  sifted, 
and  what  was  deemed  of  sufficient  importance  has  been  incorpo 
rated  in  such  detail  as  the  scope  of  the  book  permitted;  many 
changes  and  additions  suggested  by  the  experience  of  the.  authors 
have  also  been  introduced.  The  book  has,  in  brief,  been  subjected 
to  a  renewed  critical  examination  and  careful  revision.  • 

The  general  adoption  of  the  book  as  a  text  or  reference  book  in 
American  dairy  schools,  as  well  as  the  favorable  reception  which  it 
has  been  accorded  by  the  dairy  public  in  general,  will,  it  is  hoped, 
be  further  justified  by  the  present  revision.  Acknowledgment  is 
due  to  the  following  parties  for  loan  of  electrotypes,  viz.:  Cream- 
ery Pkg.  Mfg.  Co,  Chicago,  111.;  Vermont  Farm  Machine  Co., 
Bellows  Falls,  Vt. ;  D.  H.  Burrell  &  Co.,  Little  Falls,  N.  Y. ;  Henry 
Tromner,  Philadelphia,  Pa.;  Torsion  Balance  Co.,  New  York  City, 
and  Marschall  Dairy  Laboratory,  Madison,  Wis. 


TABLE  OF  CONTENTS. 


PAGE 

Introduction 1 

Chap.  I.     COMPOSITION  OF  MILK  AND  ITS  PRODUCTS 10 

Chap.  II.     SAMPLING  MILK   23 

Chap.  III.     THE  BABCOCK  TEST — MILK 28 

A.  Directions  for  making  the  test 29 

B.  Discussion  of  the  details  of  the  test 37 

Chap.  IV.     THE  BABCOCK  TEST — CREAM 75 

Chap.  V.     THE  BABCOCK  TEST — OTHER  MILK  PRODUCTS 90 

Chap.  VI.      THE  LACTOMETER  AND  ITS  APPLICATION 102 

Chap.  VII.      TESTING  THE  ACIDITY  OP  MILK  AND  CREAM 119 

Chap.  VIII.    TESTING  THE  PURITY  CF  MILK 137 

Chap.  IX.    TESTING  MILK  ON  THE  FARM 142 

Chap.  X.    COMPOSITE  SAMPLES  OF  MILK 160 

Chap.  XI.    CREAM  TESTING  AT  CREAMERIES 176 

Chap.  XII.      CALCULATION  OF  BUTTER  AND  CHEESE  YIELDS___  187 

Chap.  XIII.     CALCULATING  DIVIDENDS 203 

Chap.  XIV.     CHEMICAL  ANALYSIS   OF   MILK  AND   ITS   PROD- 
UCTS  217 

Appendix 259 

Table  I.     Composition  of  milk  and  its  products. 

Table  II.     State  ana  city  standards  for  dairy  products. 

Table  III.  Quevenne  lactometer  degrees  corresponding  to 
the  scale  of  the  M.  Y.  Board  of  Health  lactometers. 

Table  IV.     Value  of-1005^  10°  for   specific  gravities  from 

1.019  to  1.0369. 

Table  V.     Correction  table  for  specific  gravity  of  milk. 

Table  VI.  Per  cent,  of  solids  not  fat,  corresponding  to 
0  to  6  per  cent,  of  fat  and  lactometer  readings  of  26  to  36. 

Directions  for  the  use  of  Tables  VII,  VIII,  IX  and  XI. 

Table  VII.  Pounds  of  fat  in  1  to  1,000  pounds  of  milk 
testing  3  to  5.35  per  cent. 

Table  VIII.  Pounds  of  fat  in  1  to  1,000  Ibs.  of  cream  test- 
ing 12.0  to  50.0  per  cent.  fat. 


VI 


Testing  Milk  and  Its  Products. v 


Table  IX.  Amount  due  for  butter  fat,  in  dollars  and  cents, 
at  12  to  2o  cents  per  pound. 

Table  X.     Relative-value  tables. 

Table  XI.  Butter  chart,  showing  calculated  yield  of  but- 
ter, in  pounds,  from  1  to  1,000  pounds  of  milk  testing  3.0  to 
5.3  per  cent,  of  fat. 

Table  XII.  Overrun  table,  showing  pounds  of  butter  from 
100  pounds  of  milk. 

Table  XIII.  Yield  of  cheese,  corresponding  to  2.5  to  6  per 
cent,  of  fat,  with  lactometer  readings  of  26  to  36. 

Table  XIV.  Comparisons  of  Fahrenheit  and  Centigrade 
(Celcius)  thermometer  scales. 

Table  XV.  Comparison  of  metric  and  customary  weights 
and  measures. 

Table  XVI.  Specific  gravity  and  weight  of  one  gallon  of 
cream,  arranged  according  to  the  per  cent,  of  fat. 

Suggestions  regarding  the  organization  of  co-operative 
creameries  and  cheese  factories. 

Constitution  and  by-laws  for  co-operative  factory  associa- 
tions. 
Index-  ..  291 


Testing  Milk  and  Its  Products. 


INTRODUCTION. 

The  need  of  a  rapid,  accurate  and  inexpensive  method 
of  determining  the  amount  of  butter  fat  in  milk  and 
other  dairy  products  became  more  and  more  apparent, 
in  this  country  and  abroad,  with  the  progress  of  the 
dairy  industry,  and  especially  with  the  growth  of  the 
factory  system  of  butter  and  cheese  making  during  the 
last  few  decades.  So  long  as  each  farmer  made  his  own 
butter  and  sold  it  to  private  customers  or  at  the  village 
grocery,  it  was  not  a  matter  of  much  importance  to 
others  whether  the  milk  produced  by  his  cows  was  rich 
or  poor.  But  as  creameries  and  cheese  factories,  con- 
densaries  and  city  milk  plants  multiplied,  and  farm- 
ers in  the  dairy  sections  of  our  country  became  to  a 
large  extent  patrons  of  one  or  the  other  of  these,  a 
system  of  equitable  payment  for  the  milk  or  cream 
delivered  became  a  vital  question. 

i.  Nearly  all  the  creameries  in  existence  in  this  coun- 
try up  to  about  1890  were  conducted  on  the  cream- 
gathering  plan :  the  different  patrons  creamed  their 
milk  by  the  gravity  process,  and  the  cream  was  hauled 
to  the  creamery,  usually  twice  or  three  times  a  week, 
where  it  was  then  ripened  and  churned.  The  patrons 
were  paid  per  inch  of  cream  furnished.  This  quantity 
was  supposed  to  make  a  pound  of  butter,  but  cream 


2  Testing  Milk  and  Its  Products. 

from  different  sources,  or  even  from  the  same  sources 
at  different  times,  varies  greatly  in  butter-producing 
capacity,  as  will  be  shown  under  the  subject  of  cream 
testing  (2031).  The  system  of  paying  for  the  number 
of  creamery  inches  delivered  could  not  therefore  long 
give  satisfaction. 

The  proposition  to  take  out  a  small  portion,  a  pint  or 
half  a  pint,  of  the  cream  furnished  by  each  patron,  and 
determine  the  amount  of  butter  which  these  samples 
would  make  on  being  churned  in  so-called  test  churns, 
found  but  a  very  limited  acceptance,  on  account  of  the 
labor  involved  and  the  difficulty  of  producing  a  first-class 
article  from  all  the  small  batches  of  butter  thus  ob- 
tained. 

2.  The  introduction  of  the  so-called  oil  test  churn  in 
creameries,  which  followed  the  creamery-inch  system, 
marked  a  decided  step  in  advance,  and  it  soon  came 
into  general  use  in  gathered-cream  factories  (202).  In 
this  test,  glass  tubes  of  about  %  inch  internal  diameter 
and  nine  inches  long,  are  filled  with  cream  to  a  depth 
of  five  inches,  and  the  cream  is  churned;  the  tubes  are 
then  placed  in  hot  water,  and  the  column  of  melted 
butter  formed  at  the  top  is  read  off  by  means  of  a  scale 
showing  the  number  of  pounds  of  butter  per  creamery 
inch  corresponding  to  different  depths  of  melted  but- 
ter. While  the  oil  test  is  capable  of  showing  the  differ- 
ence between  good  and  poor  cream,  it  is  not  sufficiently 
accurate  to  make  satisfactory  distinctions  between  dif- 
ferent grades  of  good  and  poor  cream.2  As  a  result, 

1  Refers  to  paragraph  numbers. 

»  Wis.  Expt.  Station,  bulletin  12  (see  also  under  208). 


Introduction.  3 

full  justice  cannot  be  done  to  different  patrons  of  cream- 
eries where  payments  for  cream  delivered  are  made  on 
the  basis  of  this  test. 

3.  The  problem  of  just  payment  for  the  milk  fur- 
nished by  different  patrons  at  cheese  factories,  con- 
densaries  and  city  milk  plants  is  no  less  perplexing 
than  in  the  case  of  gathered-cream  factories.    By  the 
pooling  system   formerly   adopted,    each   patron   re- 
ceived   payment    in    proportion    to    the    number     of 
pounds  of  milk  delivered,  irrespective  of  its  quality. 
Patrons  delivering  rich  milk  naturally  will  not  be  sat- 
isfied with  this  system  when  they  find  that  their  milk 
is  richer  than  that  of  their  neighbors.    The  temptation 
to  fraudulenty  increase  the  amount  of  milk  delivered 
by  watering,  or  to  lower  its  quality  by  skimming,  will 
furthermore  prove  too  strong  for  some  patrons;  the 
fact  that  it  was  difficult  to  prove  any  fraud  committed, 
from  lack  of  a  reliable  and  practical  method  of  milk 
analysis,  rendered  this  pooling  system  still  more  ob- 
jectionable. 

4.  Formerly  private  dairymen  and  breeders  of  dairy 
cattle  who  desired  to  ascertain  the  butter-producing  ca- 
pacities  of  the   individual   cows   in   their  herds   were 
obliged  to  do  this  by  the  cumbersome  method  of  trial 
churnings :  by  saving  the  milk  of  each  cow  to  be  tested, 
for  a  day  or  a  week,  and  churning  separately  the  cream 
obtained.     This  requires  a  large  amount  of  work  when 
a  number  of  cows  are  to  be  tested,  and  can  not  therefore 
be  done  except  with  cows  of  great  excellence  or  by  farm- 
ers having  plenty  of  hired  help.    Here  again  the  need  of 
a  practical  milk  test  was  strongly1  felt. 


4  Testing  Milk  and  Its  Products. 

5.  Introduction  of  milk  tests.  The  first  method 
which  fulfilled  all  reasonable  demands  of  a  practical 
and  reliable  milk  and  cream  test  was  the  Babcock  test, 
invented  by  Dr.  S.  M.  Babcock,  of  the  Wisconsin  agri- 
cultural experiment  station.  A  description  of  the  test 
was  first  published  in  July,  1890,  as  bulletin  No.  24  of 
that  Station,  entitled:  A  new  method  for  the  estimation 
of  fat  in  milk,  especially  adapted  to  creameries  and 
cheese  factories.  This  test,  which  is  now  known  in  all 
parts  of  the  world  where  dairying  is  an  important  in- 
dustry, was  not,  however,  the  first  method  proposed  for 
this  purpose  which  could  be  successfully  operated  out- 
side of  chemical  laboratories.  It  was  preceded  by  a  num- 
ber of  different  methods,  the  first  one  published  in  this 
country  being  Short's  method,  invented  by  the  late  F. 
G.  Short,  and  described  in  bulletin  No.  16  of  Wisconsin 
experiment  station  (July  1888). 

6.  Short's  test.      In  this  ingenious  method,    a   certain   quan- 
tity of   milk    (20   cc.1)    was  boiled   with  an  alkali   solution    and 
afterwards  with  a  mixture  of  sulfuric  and  acetic  acids;   a  layer 
of  insoluble  fatty  acids  separated  on  top  of  the  liquid  and  was 
brought  into  the  graduated  neck  of  the  test  bottles  by  addition 
of  hot  water;  the  reading  gave  the  per  cent,  of  fat  in  the  sam- 
ple of  milk  tested. 

Short's  method  did  not  find  very  wide  application,  both  be- 
cause it  was  rather  lengthy  and  its  manipulations  somewhat  dif- 
ficult for  non-chemists,  and  because  several  other  methods  were 
published  shortly  after  it  had  been  given  to  the  public. 

7.  Other  milk  tests.       Of   these   may   be   mentioned,   besides 
the   Babcock    test   already   spoken    of,    the   Failyer   and    Willard 
method,*  Parsons'  method,'  Cochran's  test,*  the  Patrick  or  Iowa 

1  See  48,  footnote. 

2  Kansas  experiment  station  report,  1888,  p.  149. 
»N.  H.  experiment  station  jeport,  1888,  p.  69. 
'Journal  of  Anal.  Chem.,  Ill  (1889),  p.  381. 


Introduction.  5 

station  test,1  and  the  Beimling  (Leffmann  and  Beam)  test.*  Of 
foreign  methods  published  at  about  the  same  time,  or  previously, 
the  Lactocrite,8  Liebermann's  method,4  the  Schmid,*  Thorner,* 
Nahm,7  Rose-Gottlieb,8  sin-acid  method,9  and  the  Gerber  sal- 
me'thod1'  may  be  noted. 

8.  All  these  tests  were  similar  in  principle,  the  solids 
not  fat  of  the  milk  being  in  all  cases  dissolved  by  the 
action  of  one  or  more  chemicals,  and  the  fat  either 
measured  as  such  in  a  narrow  graduated  tube,  or 
brought  into  solution  with  ether,  gasoline,  etc.,  and  a 
portion  thereof  weighed  on  evaporation  of  the  solvent. 
While  this  principle  is  an  old  one,  having  been  em- 
ployed in  chemical  laboratories  for  generations,  its 
adaptation  to  practical  conditions,  and  the  details  as 
to  apparatus  and  chemicals  used  were,  of  course,  new 
and  different  in  each  case.  The  American  tests  given 
were  adopted  to  a  limited  extent  within  the  states  in 
which  they  originated  and  even  outside  of  them,  as  in 
the  case  of  the  Short,  Patrick  and  Beimling  methods. 
The  Babcock  test,  however,  soon  replaced  the  different 
methods  mentioned,  and  during  the  past  twenty-five 
years  it  has  now  been  in  almost  exclusive  use  in 
creameries,  cheese  factories,  condensaries,  and  city 
milk  plants  in  this  country,  where  payments  are  made 

1  la.  exp.  sta.,  bull.  No.  8,  Feb.  1890 ;  Iowa  Homestead,  June  14,  1889. 

2  Vermont  exp.  sta.,  bull.  No.  21,  September,  1890.     For  description 
of  these  and  other  volumetric  methods  of  milk  analysis,  see  Wiley,  Agri- 
cultural Analysis,  Vol.  Ill,  p.  490  et  seq.  ;  Wing,  Milk  and  its  Products, 
p.  33  et  seq.,  and  Snyder,  Chemistry  of  Dairying,  pp.  112-113. 

3  Analyst,   1887,   p.   0. 

4  Fresenius'  Zeitschr.,  22,  383. 

5  Ibid.,    27,    4G4. 

8  Chem.  Centralbl.,  1892,  429. 

T  Milch-Zeitung,  1894,  No.  35 ;  1897,  No.  50. 

8  Landw.  Vers.  Stat.,  40,  1. 

•  Milch-Zeitung,   1904,  No.  27. 

'•Milch-Zeitung,  1906,  No.  8. 


6  Testing  MUk  and  Its  Products. 

on  the  basis  of  the  quality  of  the  milk  delivered, 
as  well  as  in  the  routine  work  in  experiment  sta- 
tion laboratories,  and  among  milk  inspectors  and  pri- 
vate dairymen. 

9.  The  Babcock  test.     The    main    cause    why    the 
Babcock  test  has  replaced  all  competitors  is  doubtless 
to  be  sought  in  its  simplicity  and  its  cheapness.    It  has 
but  few  manipulations,  is  easily  learned,  and  is  cheap, 
both  in  first  cost  and  as  regards  running  expenses. 

The  test  is  furthermore  speedy,  accurate,1  and  easily 
applied  under  practical  conditions,  and  may  therefore 
safely  be  considered  the  best  milk  test  available  at  the 
present  time. 

The  method  is  applicable  not  only  to  whole  milk,  but 
to  cream,  skim  milk,  butter  milk,  whey,  condensed  milk, 
and  (if  a  small  scale  for  weighing  out  the  sample  is 
available)  to  cheese  and  butter.2 

With  all  its  advantages,  the  Babcock  milk  test  is  not 
in  every  respect  an  ideal  test.  The  handling  of  the 
very  corrosive  sulfuric  acid  requires  constant  care  and 
attention;  the  speed  of  the  tester,  the  strength  of  the 
acid,  the  temperature  of  the  milk  to  be  tested,  and  other 
points,  require  constant  watching,  lest  the  results  ob- 
tained be  too  low  or  otherwise  unsatisfactory.  In  the 
hands  of  careful  operators  the  test  can,  however,  al- 
ways be  relied  upon  to  give  most  satisfactory  results. 

10.  Foreign  methods.      In    European    countries 
several  practical  milk  and  cream  tests,  besides  the  Bab- 

1  For  a  summary  of  comparative  analyses  made  by  the  Babcock  test 
and  gravimetric  analysis  up  to  1892,  see  Hoard's  Dairyman,  Oct.  7,  1892, 
p.  2560;  also  Schrott-Flechtl,  Mllchzeltung,  1896,  p.  183  et  seq. 

'The  Babcock  test,  like  the  ether-extraction  method  gives,  however, 
somewhat  too  low  results  in  the  case  of  skim  milk  and  other 
dairy  products  low  In  fat  (97). 


Introduction.  7 

cock  test,  are  in  the  use  at  the  present  time,  viz: 
Gerber' s  acid-butyro meter,  the  sin-acid  (or  no-acid)  test,  the 
lactocrite,  De  Laval's  butyrometer,  and  Fjord's  centrifugal 
cream  test.1 

Of  these  tests  the  last 
one  has  never,  to  our 
knowledge,  been  intro- 
duced into  this  country, 
and  the  first  four  only  to 
a  limited  extent. 

11.    The  Gerber  [method 

(fig.  1)  is  essentially  the  old 
Beimling  method  (7),  worked 
out  independently  by  the 
Swiss  chemist,  Dr.  N.  Gerber. 
In  this  test  sulfuric  acid  of 
the  same  strength  as  in  the 

Babcock   test  is  used,   and  a 

„  ,.,        .          ,     ,  Fio.  1.     The  Gerber  acid- 

small  quantity  of  amyl  alco-  butyrometer. 

hoi  is  added.  The  amyl  alcohol  facilitates  the  separation  of  the 
fat,  but  may  introduce  a  source  of  error  on  account  of  impuri- 
ties contained  therein,  when  the  results  obtained  with  a  new  lot  of 
alcohol  can  not  be  checked  against  gravimetric  analysis  or  against 
tests  made  with  amyl  alcohol  known  to  give  correct  results.  This 
method  is,  however,  extensively  used  in  European  countries,  hav- 
ing there  practically  replaced  the  Babcock  test  or  been  adopted 
in  preference  to  it. 

1  la.  The  sin-acid  test  was  invented  by  the  German  chemist 
A.  Sichler  and  published  in  1904.»  In  place  of  the  sulfuric  acid 
used  in  the  Babcock  and  Gerber  tests,  Sichler  employs  a  solution  of 

1  The  Lister-Iiabcock  milk  test  advertised  in  English  papers  and 
known  as  such  in  England,  is  the  regular  Babcock  test,  to  which  the 
English  manufacturers  have  affixed  their  name;  the  same  applies  to  the 
Ahllorn-Babcuck  and  the  Krugmann-Babcock  methods. 

1  Gerber,  Die  praktiscbe  Milch  priifung,  7th  edition,  1900. 

•Milchztg.,  1904,  p.  417.  The  word  sin  (sine)  is  Latin  and  means 
without;  hence,  when  introduced  Into  this  country  in  1909  the  method 

was  called  the  no-acid  test. 


8  Testing  Milk  and  Its  Products. 

Rochelle  salts,  sodium  sulfate  and  sodium  hydroxid.1  150  cc.  of  this 
mixture  of  salts  are  dissolved  in  1  liter  of  water.  In  testing  milk, 
11  cc.  of  this  solution  and  0.6  cc.  of  "sinol"  (isobutylalcohol)  are 
added  to  10  ec.  of  milk.  After  thorough  mixing  of  the  milk  and 
solution  the  test  bottles  are  placed  in  water  of  113°  F.  for  3-5 
minutes,  when  they  are  shaken  till  all  the  curd  dissolves.  They 
are  then  revolved  in  a  centrifuge  for  3  minutes  and  the  results  read 
off.  By  heating  the  bottles  for  1  hour  in  boiling  hot  water  correct 
results  may  be  obtained  without  the  use  of  a  centrifuge.  The 
main  advantages  of  the  method  appear  to  lie  in  this  fact  and  in 
that  the  use  of  a  corrosive  acid  is  avoided. 

12.  The  Lactocrite  was  one  of  the  earliest  practical  milk 
tests  introduced.  It  was  invented  by  De  Laval  in  1886.  The 
acids  used  in  this  test  are  lactic  acid  (originally,  acetic  acid) 
with  a  mixture  of  hydrochloric  and  sulfuric  acids.  This  test  is- 
now  but  rarely  met  with. 


Fio.  2.     De  Laval's  butyrometer. 

,  13.  In  the  De  Laval  butyrometer  (fig.  2)  the  same  acid  is 
used  as  in  the  Babcock  test,  but  the  tubes  employed  and  the 
manipulations  of  the  method  differ  materially  from  this  test;  a 
smaller  sample  of  milk  is  taken  (only  2  cc.)  and  a  correspond- 
ingly small  quantity  of  acid  used.  Where  a  large  number  of 

'  Barthel-Goodwin,  Methods  used  in  Examination  of  Milk  and  Dairy 
Products,  p.  77. 


Introduction,  9 

milk  samples  are  tested  every  day,  as,  for  instance,  in  milk  control 
stations,  the  butyrometer  may  be  preferable  to  the  Babcock  test; 
but  it  requires  more  skill  of  the  operator  and  does  not  work  satis- 
factorily in  case  of  sour,  loppered,  or  partially  churned  milk. 

14.  Fjord's  centrifugal  cream  tester1  •  (fig-  3)  is  exten- 
sively used  in  Denmark  and  is  mentioned  in  this  connection  as  it 
furnishes,  as  a  rule,  a  reliable  method  for  comparing  the  qual- 
ity of  different  lots  of  milk.  The  method  was  published  in  1878, 
by  the  late  N.  J.  Fjord,  director  of  the  state  experiment  station 
in  Copenhagen,  through  whose  exertions  and  on  whose  authority 
it  was  introduced  into  Danish  creameries  in  the  middle  of  the 
eighties.  No  chemicals  are  added  in  this  test,  the  milk  being 
simply  placed  in  glass  tubes,  seven  inches  long  and  about  two 
thirds  of  an  inch  in  diameter,  and  whirled  for  twenty  minutes 
at  a  rate  of  2000  revolutions  per  minute  at  55°C  (131°F.). 
The  reading  of  the  cream  layer  thus  obtained  gives  the  per  cent 
of  cream,  and  not  of  butter 
fat,  in  the  sample  tested.  One 
hundred  and  ninety-two  sam- 
ples of  milk  can  be  tested 
simultaneously.  Within  the 
limits  of  normal  Danish  herd 
milk,  the  results  obtained  cor- 
respond to  the  per  cents  of  fat 
present  in  the  samples,  one  per 
cent,  of  cream  being  equal  to 
about  0.7  per  cent,  of  fat ;  FIG.  3.  FJord7s^entrlfugal  cream 
outside  of  these  limits  the  test  tester. 

is,  however,  unreliable,  especially  in  case  of  very  rich  milk  and 
strippers'  milk.  Only  sweet  milk  can  be  tested  by  this  method. 
Milk  tests  proper,  like  the  Gerber,  Babcock  and  De  Laval  tests, 
have  during  recent  years  been  introduced  into  Denmark  and 
are  used  in  some  creameries.2 

1  State  Danish  experiment  station,  Copenhagen,  sixth  and  ninth  re- 
ports, 1885-7. 

2  Among  foreign  milk  tests  in  use  abroad  should  also  be  mentioned 
the   Lindstrom    butyrometer   and    the    Wollny   refractometer,   both    of 
which,  in  the  hands  of  trained  chemists,  may  prove  better  adapted  for 
use  where  a  very  large  number  of  samples  are  to  be  tested  at  a  time, 
than  any  other  available  milk  test. 


-       CHAPTER  1. 
COMPOSITION    OF   MILK  AND   ITS   PRODUCTS. 

Before  taking  up  the  discussion  of  the  Babcock  milk 
test,  a  brief  description  of  the  chemistry  of  milk  and  its 
products  is  given,  so  that  the  student  may  understand 
what  are  the  components  of  dairy  products,  and  the  re- 
lation of  these  to  each  other.  Only  such  points  as  have 
a  direct  bearing  upon  the  subject  of  milk  testing  at 
manufacturing  and  distributing  plants  will  be  treated 
in  this  chapter,  and  the  reader  is  referred  to  standard 
works  on  dairying  for  more  detailed  information  in 
regard  to  the  composition  of  dairy  products. 

15.  Composition  of  milk.  Milk  is  composed  of  the 
following  substances:  water,  fat,  casein,  albumen,  milk 
sugar,  and  ash.  A  few  other  substances  are  present  in 
small  quantities,  but  they  are  hardly  of  sufficient  prac- 
tical importance  to  be  considered  here.  The  com- 
ponents of  the  milk  less  the  water  are  known  collect- 
ively as  muk  solids  or  total  solids,  and  the  total  solids 
less  the  fat,  i.  e.,  casein,  albumen,  milk  sugar,  and  ash, 
are  often  spoken  of  as  solids  not  fat  or  the  non-fatty 
milk  solids.  The  milk  serum  includes  all  components 
of  the  milk  less  the  fat;  the  serum  solids  are  therefore 
another  name  for  the  solids  not  fat;  when  given,  they 
are,  however,  generally  calculated  to  per  cent,  of  milk 
serum,  not  of  milk.  If,  e.  g.,  a  sample  of  milk  contains 


Composition  of  Milk  and  Its  Products.          11 

nine  per  cent,  of  solids  not  fat,  and  three  per  cent,  of 
fat,  the  milk  serum  will  make  up  97  per  cent,  of  the 

milk,  and  the  serum  solids,   9X10°    =9.28  per  cent,  of 

the  milk  serum. 

16.  Water.    The  amount  of  water  contained  in  cow's 
milk  ranges  from  82  to  90  per  cent.    Normal  cow's  milk 
will  not,  as  a  rule,  contain  more  than  88  per  cent,  of 
water,  nor  less  than  84  per  cent.    In  states  where  there- 
are  laws  regulating  the  sale  of  milk,  as  is  the  case  in 
twenty-two  states  of  the  Union  (see  Appendix,  Table 
II),  the  maximum  limit  for  water  in  milk  in  all  instances 
but  one  (South  Carolina)  is  88  per  cent. ;  the  state  men- 
tioned allows  88.5  per  cent,  of  water  in  milk  offered 
for  sale  within  her  borders.    The  effect  of  fraudulently 
increasing  the  water  content  of  milk  by  watering  is  con- 
sidered under  Adulteration  of  Milk  (121). 

17.  Fat.    The  fat  in  milk  is  not  in  solution,  but  sus- 
pended as  very  minute  globules,  which  form  an  emul- 
sion with  the  milk  serum;  the  globules  are  present  in 
immense  numbers,  viz.,  on  the  average  about  one  hun- 
dred millions  in  a  single  drop  of  milk;  a  quart  of  milk 
will  contain  about  two  thousand  billions  of  fat  globules, 
a  number  written  with  thirteen  figures.     The  sizes  of 
the  globules  in  the  milk  from  the  same  cows  vary  ac- 
cording to  the  stage  of  the  period  of  lactation,  the  glob- 
ules being  largest  at  the  beginning  of  the   lactation 
period,  and  gradually  decreasing  in  size  with  its  prog- 
ress.    Different  breeds  of  cows  have  fat  globules  of 
different  average  sizes;  the  Channel  Island  cows  are 
thus  noted  for  the  relatively  large  fat  globules  of  their 


12  Testing  Milk  and  Its  Products. 

milk,  while  the  lowland  breeds,  the  Ayrshire,  and  other 
breeds  have  uniformly  smaller  globules.  The  diameter 
of  average  sized  fat  globules  in  fresh  milkers  is  about 
.004  millimeter,  or  one  six-thousandth  of  an  inch;  that 
is,  it  takes  about  six  thousand  such  globules  placed  side 
by  side  to  cover  one  inch  in  length.  The  globules  of 
any  sample  of  milk  vary  greatly  in  size;  the  largest 
globules  are  recovered  in  the  cream  when  the  milk  is 
set  or  run  through  a  cream  separator,  and  the  smallest 
ones  remain  in  the  skim  milk ;  thoroughly  skimmed  sep- 
arator skim  milk  contains  only  a  small  number  of  very 
minute  fat  globules. 

Milk  fat  is  composed  of  so-called  glycerides  of  the 
fatty  acids,  i.  e.,  compounds  of  the  latter  with  glycerin ; 
some  of  the  fatty  acids  are  insoluble  in  water,  viz., 
palmitic,  stearic,  and  oleic  acids,  while  others  are  solu- 
ble and  volatile,  the  chief  ones  among  the  latter  being 
butyric,  caprylic,  and  capronic  acids.  The  glycerides 
of  the  insoluble  fatty  acids  make  up  about  92  per  cent, 
of  the  pure  milk  fat;  about  8  per  cent,  of  the  glycer- 
ides of  volatile  fatty  acids  are  therefore  found  in  nat- 
ural milk-  (and  butter-)  fat.  The  distinction  between 
natural  and  artificial  butter  lies  mainly  in  this  point, 
since  artificial  butter  (butterine,  oleomargarine)  as  well 
as  other  solid  animal  fats  contain  only  a  very  small 
quantity  of  volatile  fatty  acids.  The  glycerides  of  the 
volatile  fatty  acids  are  unstable  compounds,  and  are 
easily  decomposed  through  the  action  of  bacteria  or 
light;  the  volatile  fatty  acids  thus  set  free,  principally 
butyric  acid,  are  the  cause  of  the  unpleasant  odor  met 
with  in  rancid  butter. 


Composition  of  Milk  and  Its  Products.          13 

Cow's  milk  generally  contains  between  three  and  six 
per  cent,  of  fat ;  in  American  herd  milk  we  find,  on  the 
average,  toward  four  per  cent,  of  fat.  The  milk  from 
single  cows  in  perfect  health  will  occasionally  go  below 
or  above  the  limits  given,  but  mixed  herd  milk  rarely 
falls  outside  of  these  limits.  The  standard  adopted  by 
the  U.  S.  government  for  fat  in  milk  is  3.25  per  ct. 
The  legal  standard  for  fat  in  milk  in  most  states  of  the 
Union  is  3  per  cent. ;  Rhode  Island  allows  milk  contain- 
ing 2.5  per  cent,  of  fat  to  be  sold  as  pure,  while  Georgia 
and  Minnesota  require  it  to  contain  3.5  per  cent.,  and 
Massachusetts  3.7  per  cent,  (in  the  months  of  May  and 
June;  see  Appendix,  Table  II). 

18.  Casein  and  albumen.  These  belong  to  the  so- 
called  nitrogenous  substances,  distinguished  from  the 
other  components  of  the  milk  by  the  fact  that  they  con- 
tain the  element  nitrogen.  Another  name  is  albumin- 
oids or  protein  compounds.  Casein  is  precipitated  by 
rennet  in  the  presence  of  soluble  calcium  salts,  and  by 
dilute  acids  and  certain  chemicals ;  albumen  is  not  acted 
upon  by  these  agents,  but  is  coagulated  by  heat,  a  tem- 
perature of  170°  F.  being  sufficient  to  effect  a  perfect 
coagulation.  The  casein,  fat,  and  water,  are  the  main 
components  of  nearly  all  kinds  of  cheese.  In  the  manu- 
facture of  cheddar  and  most  other  solid  cheeses,  the 
casein  is  coagulated  by  rennet,  and  the  curd  thus 
formed  holds  fat  and  whey  mechanically,  the  latter 
containing  in  solution  small  quantities  of  non-fatty 
milk  solids.  The  albumen  goes  into  the  whey  and  is 
lost  for  cheese  making ;  in  some  countries  it  is  also  made 
into  cheese  by  evaporating  the  whey  under  constant 


14  Testing  Milk  and  Its  Products. 

stirring;  whole  milk  of  cows  or  goats  is  often  added  and 
incorporated  into  such  cheese  (primost,  gjetost). 

Casein  is  present  in  milk  partly  in  solution,  in  the 
same  way  as  milk  sugar,  soluble  ash-materials  and  albu- 
men, and  partly  in  suspension,  in  an  extremely  fine  col- 
loidal condition,  mixed  or  combined  with  insoluble  cal- 
cium phosphates.  The  casein  and  calcium  phosphates 
in  suspension  in  milk  may  be  retained  on  a  filter  made 
of  porous  clay  (so-called  Chamberland  filters). 

About  80  per  cent,  of  the  nitrogenous  compounds  of 
normal  cow's  milk  are  made  up  of  casein;  the  rest  is 
largely  albumen.  If  the  amount  of  casein  in  milk  be 
determined  by  precipitation  wjth  rennet  or  dilute  acids, 
and  the  albumen  by  boiling  the  filtrate  from  the  casein 
precipitate,  it  will  be  found  that  the  sum  of  these  two 
compounds  do  not  make  up  the  total  quantity  of  nitro- 
genous constituents  in  the  milk.  The  small  remaining 
portion  (about  five  per  cent,  of  the  total  nitrogenous 
constituents)  has  been  called  by  various  authors,  globu- 
lin, albumose,  hemi-albumose,  nuclein,  nucleon,  proteose, 
etc.  The  nitrogenous  constituents  of  milk  are  very  un- 
stable compounds,  and  their  study  presents  many  and 
great  difficulties ;  as  a  result  we  find  that  no  two  scien- 
tists who  have  made  a  special  study  of  these  compounds 
agree  as  to  their  properties,  aside  from  those  of  casein 
and  albumen,  or  their  relation  to  the  nitrogenous  sub- 
stances found  elsewhere  in  the  animal  body.  For  our 
purpose  we  may,  however,  consider  the  nitrogen  com- 
pounds of  milk  as  made  up  of  casein  and  albumen,  and 
the  term  casein  and  albumen,  as  used  in  this  book,  is 
meant  to  include  the  total  nitrogenous  constituents  of 


Composition  of  Milk  and  Its  Products.  15 

milk,  obtained  by  multiplying  the  total  nitrogen  con- 
tent of  the  milk  by  6.25.1 

The  quantity  of  casein  in  normal  cow's  milk  varies 
from  2  to  4  per  cent.,  and  of  albumen,  from  .5  to  .8  per 
cent.  The  total  content  of  casein  and  albumen  ranges 
between  2.5  and  4.6  per  cent,  the  average  being  about 
3.2  per  cent.  Milk  with  a  low  fat  content  will  contain 
more  casein  and  albumen  than  fat,  while  the  reverse  is 
generally  true  in  case  of  milk  containing  more  than  3.5 
per  cent,  of  fat. 

19.  Milk  sugar  or  lactose  belongs  to  the  group  of 
organic  compounds  known  as  carbohydrates.  It  is  a 
commercial  product  manufactured  from  whey  and  is 
obtained  in  this  process  as  pale  white  crystals,  of  less 
sweet  taste  and  less  soluble  in  water  than  ordinary 
sugar  (cane  sugar,  sucrose).  About  70  per  cent,  of  the 
solids  in  the  whey,  and  33  per  cent,  of  the  milk  solids, 
are  composed  of  milk  sugar. 

When  milk  is  left  standing  for  some  time,  viz.,  from 
one  to  several  days,  according  to  its  cleanliness  and 
the  temperature  of  the  surrounding  medium,  it  will 
turn  sour  and  soon  become  thick  and  loppered.  This 
change  in  the  composition  and  appearance  of  the  milk 
is  brought  about  through  the  action  of  acid-forming 
bacteria  on  the  milk-sugar.  These  are  present  in  ordi- 
nary milk  in  immense  numbers,  and  under  favorable 
conditions  of  temperature  multiply  rapidly,  feeding  on 

1  The  factor  6.25  is  generally  used  for  obtaining  the  casein  and  albu- 
men from  the  total  nitrogen  in  the  milk,  on  the  theory  that  protein 
compounds  contain  16%  N. ;  the  factor  6.37  would,  however,  be  more 
correct,  since  casein  and  albumen,  according  to  our  best  authorities, 

100 
15.7 


16  Testing  Milk  and  Its  Products. 

the  milk  sugar  as  they  grow,  and  decomposing  it  into 
lactic  acid.  When  this  change  alone  occurs,  there  is 
not  necessarily  a  loss  in  the  nutritive  value  of  the  milk, 
since  milk  sugar  breaks  up  directly  into  lactic  acid. 
This  is  shown  by  the  following  chemical  formula : 

C12H230UH20   (lactose)  =4  C3H603  (lactic  acid}.1 

Ordinarily  the  souring  of  milk  is,  however,  more 
complicated,  and  other  organic  bodies,  like  butyric  acid, 
alcohol,  etc.,  and  gases  like  carbonic  acid  are  formed, 
resulting  in  a  loss  in  the  feeding  value  of  the  milk. 
While  sour  milk  may  therefore  contain  a  somewhat 
smaller  proportion  of  food  elements  than  sweet  milk, 
it  will  generally  produce  better  results  when  fed  to 
farm  animals,  especially  pigs,  than  is  obtained  in  feed- 
ing similar  milk  in  a  sweet  condition.  The  cause  of  this 
may  lie  in  the  stimulating  effect  of  the  lactic  acid  of 
sour  milk  on  the  appetites  of  the  animals,  or  in  its  aid- 
ing digestion  by  increasing  the  acidity  of  the  stomach 
juices. 

That  the  souring  of  milk  is  due  to  the  activities  of 
bacteria  present  therein  is  shown  clearly  by  the  fact 
that  sterile  milk,  i.  e.,  milk  in  which  all  germ  life  has 
been  killed,  will  remain  sweet  for  any  length  of  time 
when  kept  free  from  infection. 

The  amount  of  milk  sugar  found  in  normal  cow's 
milk  varies  from  3.5  to  6  per  cent.,  the  average  content 
being  about  5  per  cent. ;  in  sour  milk  this  content  is 
decreased  to  toward  4  per  .cent. 

1  One  molecule  of  milk  sugar  is  composed  of  12  atoms  of  carbon  (C), 
22  atoms  of  hydrogen  (H),  11  atoms  of  oxygen  (O),  and  one  molecule 
of  water  (H2O).  In  the  same  way,  the  lactic  acid  molecule  consists  of  3 
atoms  of  carbon,  6  atoms  of  hydrogen,  and  3  atoms  of  oxygen. 


Composition  of  Milk  and  Its  Products.  17 

20.  Ash.     The  ash  or  mineral  substances  of  milk  are 
largely  composed  of  chlorids  and  phosphates  of  sodium, 
potassium,  magnesium  and  calcium;  iron  oxid  and  sul 
furic  and  other  acids  are  also  present  in  small  quanti 
ties  among  the  normal  mineral  milk  components.     Thr 
amounts  of  the  different  bases  and  acids  found  in  milk 
ash  have  been  determined  by  a  number  of  chemists ;  the 
average   figures    obtained    are   given    in    the    following 
table,  calculated  per  100  parts  of  milk  (containing  .75 
per  cent,  of  ash)  and  per  100  parts  of  milk  ash. 

Mineral  Components  of  Milk. 

In  per  cent  of  milk.     In  per  cent  of  ash 

Potassium  oxid  (K2O) .19  per  ct.  25.64  per  ct. 

Sodium  oxid    ^Na,O) —     .09  12.45 

Lime  (CaO) .18  24.58 

Magnesia  (.MgO; .02  3.09 

Iron  oxid  (FejO,) .002  .34 

Phosphoric  anhydrid   (P2OB)_—     .16  21.24 

Chlorin  (01) .12  16.34 


.762  per  ct.  103.68  per  ct. 

chlorin__.  .012  3.68 


Less  oxygen,  corresponding  to 
" "  rin_. 


.75  100.00 

The  combinations  in  which  the  preceding  bases  and 
acids  are  contained  in  the  milk  are  not  known  with  cer- 
tainty. According  to  Soldner,  36  to  56  per  cent,  of  the 
phosphoric  acid  found  in  milk,  and  from  53  to  72  per 
cent,  of  the  lime,  are  present  in  suspension  in  the  milk 
as  di-  and  tri-calcium  phosphates,  and  may  be  separated 
out  by  means  of  Chamberland  filters  (18),  or  by  long- 
continued  centrifuging  (Babcock1).  The  rest  of  the 
ash  constituents  are  dissolved  in  the  milk  serum. 

1  Wisconsin  experiment  station   report  12,  p.  93. 

2 


18  Testing  Milk  and  Its  Products. 

The  ash  content  of  normal  cow's  milk  varies  but  lit- 
tle, as  the  rule  only  between  .6  and  .8  per  cent.,  with  an 
average  of  .7  per  cent.  Milk  with  a  high  fat  content 
generally  contains  about  .8  per  cent,  of  ash;  strippers' 
milk  always  has  a  high  ash  content,  at  times  even  ex- 
ceeding one  per  cent.  Ordinarily,  the  mineral  constitu- 
ents are  least  liable  to  variations  of  any  of  the  com- 
ponents of  the  milk. 

21.  Other  components.     Besides  the  milk  constitu- 
ents enumerated  and  described  in  the  preceding  pages, 
normal  milk  contains  a  number  of  substances  which  are 
present  in  but  small  quantities  and  have  only  scientific 
interest,  such  as  the  milk  gases  (carbonic  acid,  oxygen, 
nitrogen),  citric  acid,  lecithin,  cholesterin,  urea,  hypo- 
xanthin,  lactochrome,  etc. 

22.  Average  composition.     The  average  percentage 
composition  of  cow's  milk  will  be  seen  from  Table  I  in 
the  Appendix.    The  following  statement  shows  the  lim- 
its within  which  the  components  of  normal  American 
cows'  milk  are  likely  to  come: 

Minimum.  Maximum.  Average. 

Water 82.0  per  ct.  90.0  per  ct.  87.4  per  ct. 

Pat 2.3  7.8  3.7 

Casein  and  albumen 2.5  4.6  3.2 

Milk  sugar 3.5  6.0  5.0 

Ash .6  .9  .7 

23.  Colostrum    milk.     The   liquid   secreted   directly 
after  parturition  is  known  as  colostrum  milk  or  biest- 
ings.     It  is  a  thick,  yellowish,  viscous  liquid;  its  high 
contents  of  albumen  and  ash  are  characteristic,  and  also 
its  low  content  of  milk  sugar.    Owing  to  the  large  quan- 
tity of  albumen  which  colostrum  contains,  it  will  coajrii 


Composition  of  Milk  and  Its  Products.          19 

late  on  being  heated  toward  the  boiling  point.  In  the 
course  of  three  or  four  days  the  secretion  of  the  udder 
gradually  changes  from  colostrum  to  normal  milk;  the 
milk  is  considered  fit  for  direct  consumption  or  for  the 
manufacture  of  cheese  and  butter,  when  it  does  not  co- 
agulate on  boiling  and  is  of  normal  appearance  as  re- 
gards color,  taste,  and  other  properties.  For  composi- 
tion of  colostrum  milk,  see  Appendix,  Table  I. 

24.  Composition  of  milk  products.  In  addition  to 
its  use  for  direct  consumption,  milk  is  the  raw-material 
from  which  cream,  butter,  cheese,  ice  cream  and  con- 
densed milk  are  obtained. 

When  milk  is  left  standing  for  some  time  or  subjected 
to  centrifugal  force,  it  will  separate  into  two  distinct 
parts,  cream  and  skim  milk.  The  proportion  of  each 
part  which  is  obtained,  and  their  chemical  composition, 
will  depend  on  the  method  by  which  the  separation  is 
effected;  in  the  so-called  gravity  process  where  the 
cream  is  separated  on  standing— either  in  shallow  pans 
in  the  air,  or  in  deep  cans,  submerged  in  cold  water— a 
less  complete  separation  is  reached,  and  the  skim  milk 
obtained  is  richer  in  fat  than  when  the  separation  takes 
place  through  the  action  of  centrifugal  force. 

In  modern  creameries  the  milk  is  now  always  skimmed 
by  means  of  cream  separators.  Separator  cream  will 
contain  from  15  to  50  per  cent,  of  fat,  according  to  the 
adjustment  of  the  separator  and  of  the  milk  supply; 
ordinarily  it  contains  about  25  per  cent,  of  fat.  Cream 
of  average  quality,  in  addition  to  the  fat  content  given, 
consists  of  about  66  per  cent,  of  water,  3.8  per  cent 


20  Testing  Milk  and  Its  Products. 

casein  and  albumen,  4.3  per  cent,  milk  sugar,  and  .5  per 
cent.  ash. 

The  skim  milk  is  made  up  of  the  milk  serum  (15)  and 
a  small  amount  of  fat,  viz.,  toward  .4  per  cent,  when 
obtained  by  the  gravity  process,  and  less  than  .2  per 
cent,  in  the  case  of  separator  skim  milk.  Milk  set  in 
shallow  pans  in  the  air,  or  in  deep  cans  in  water  above 
60°  P.,  will  give  skim  milk  containing  one-half  to  over 
one  per  cent,  of  fat.  Skim  milk  is  used  as  a  food  for 
young  farm  animals  or  as  human  food,  and  for  the 
manufacture  of  cheese  and  casein. 

25.  Cream  is  used  for  the  manufacture  of  butter  or 
for  direct  consumption.  In  the  -former  case  a  certain 
amount  of  acidity  is  generally  allowed  to  develop  there- 
in previous  to  the  churning  process.  This  secures  a 
more  complete  churning  and  produces  peculiar  flavors 
in  the  butter,  without  which  it  would  seem  insipid  "to 
most  people.  Nearly  all  butter  made  in  this  coun 
try  is  salted  before  being  placed  on  the  market 
Salt  is  a  preservative  and  for  a  limited  length  of 
time  prevents  butter  from  spoiling.  Unsalted  butter 
made  from  sweet  cream  is  a  common  food  article  in 
Southern  and  Middle  Europe,  but  only  an  insignificant 
amount  is  manufactured  and  consumed  in  America; 
salted  butter  made  in  Europe  also  contains  considerably 
less  salt  than  American  butter  (see  Appendix,  Table  I) . 
Butter  contains  all  the  fat  of  the  cream  except  a  small 
portion  which  goes  into  the  butter  milk,  and  a  small 
unavoidable  mechanical  loss  incident  to  the  handling  of 
the  products.  Butter  should  contain  at  least  80  per 


Composition  of  Milk  and  Its  Products.  21 

cent,  of  fat  and  ordinarily  contains  about  83  per  cent. ; 
besides  this  amount  of  fat,  butter  is  generally  composed 
of  about  13  per  cent,  water,  1  per  cent,  curd  and  lactic 
acid,  and  3  per  cent.  salt. 

Butter  milk  has  a  composition  similar  to  skim  milk, 
but  varies  much  more  than  this  product,  according  to 
the  acidity,  temperature,  and  thickness  of  the  cream, 
and  other  churning  factors.  It  contains  about  9  per 
cent,  of  solids,  viz.,  milk  sugar  (and  lactic  acid)  4  per 
cent.,  casein  and  albumen  4  per  cent.,  fat  .3  per  cent., 
and  ash  .7  per  cent. 

26.  The  quantities  of  butter  and  by-products  obtained 
in  the  manufacture  of  butter  are  as  follows:    1000  Ibs. 
of  milk  of  average  quality  will  give  about  850  Ibs.  of 
skim  milk  and  145  Ibs.  of  cream   (separator  slime  and 
mechanical  loss,  5  Ibs.) ;  this  amount  of  cream  will  make 
about  42  Ibs.  of  butter  and  100  Ibs.  of  butter  milk  (me- 
chanical loss,  3  Ibs.). 

27.  In  the  manufacture  qf  American  cheddar  cheese, 
whole  milk  is  heated  to  about  86°  F.,  and  a  small  amount 
of  rennet  extract  is  added,  which  coagulates  the  casein; 
the  albumen  of  the  milk  is  not  precipitated  by  rennet 
and  remains  in  solution  (18).  "Green"  cheese,  as  taken 
from  the  press,  is  made  up,  roughly  speaking,  of  37  per 
cent,  of  water,  34  per  cent,  of  fat,  24  per  cent,  of  albu- 
minoids  (nearly  all  casein),  and  about  5  per  cent,  of 
milk  sugar,  lactic  acid,  and  ash  (largely  salt).    In  the 
curing  of  cheese  there  is  some  loss  by  drying,  but  the 
main  changes  occur  in  the  breaking  up  of  the  firm  curd 
into  soluble  and  digestible  nitrogenous  compounds,  pep- 
tones, amids,  etc. 


22  Testing  Milk  and  Its  Products. 

Whey  is  the  by-product  obtained  in  the  manufacture 
of  cheese.  It  consists  of  water  and  less  than  7  per  cent, 
of  solids;  of  the  latter  about  5  per  cent,  is  milk  sugar, 
.8  per  cent,  albumen,  .6  per  cent,  ash,  and  .3  per  cent, 
fat.  Whey  is  generally  used  for  feeding  farm  animals ; 
it  is  the  raw-material  from  which  milk  sugar  and  whey 
cheese  are  made. 

28.  Condensed  milk  is  manufactured  from  whole  milk 
or  from  partially  skimmed  milk.  In  many  brands  a 
large  quantity  of  sugar  (25  per  cent,  or  more)  is  added 
to  the  condensed  milk  in  the  process  of  manufacture  so 
as  to  secure  perfect  keeping  quality  in  the  product. 
Brands  to  which  no  sugar  has  been  added  are  also  on 
the  market,  and  in  case  of  such  brands  the  relation  be- 
tween the  various  solid  constituents  of  the  condensed 
milk  will  be  essentially  the  same  as  that  between  the 
constituents  of  milk  solids.  Condensed  milk  should  con- 
tain not  less  than  8%  fat,  and  must  be  free  from  pre- 
servatives and  other  foreign  substances  (except  sugar). 

Tables  are  given  in  the  Appendix  showing  the  aver- 
age composition  of  the  various  milk  products. 


Questions. 

1.  What  is  the  average  composition  of  cow 's  milk ;  state  briefly 
the  properties  of  the  various  constituents. 

2.  What  is  meant  by  total  solids;  solids  not  fat;  milk  serum; 
serum  solids  f 

3.  What  is  colostrum  milk?     Give  its  average  composition,  and 
in  what  particulars  it  mainly  differs  from  normal  milk. 

4.  Give  the  average  composition  of  cream,  skim  milk,  butter 
milk,  whey,  butter  and  cheddar  cheese. 

5.  Explain  the  distribution  of  the  components  of  milk  in    (a) 
butter-making,  (b)  cheese-making. 


CHAPTER  II. 
SAMPLING   MILK. 

29.  The  butter  fat  in  milk  is  not  in  solution,  like 
sugar  dissolved  in  water,  but  the  minute  fat  globules  or 
drops,  in  which  form  it  occurs,  are  held  in  suspension 
in  the  milk  serum  (17).  Being  lighter  than  the  serum, 
the  fat  globules  have  a  tendency  to  rise  to  the  surface 
of  the  milk.  If,  therefore,  a  sample  of  milk  is  left 
standing  for  even  a  short  time,  the  upper  layer  will 
contain  more  fat  than  the  lower  portion.  This  fact 
should  always  be  borne  in  mind  when  milk  is  sampled. 
The  rapidity  with  which  fat  rises  in  milk  can  be  easily 
demonstrated  by  allowing  a  quantity  of  sweet  milk  to 
stand  in  a  cylinder  or  a  milk  can  for  a  few  minutes, 
and  testing  separately  the  top,  middle  and  bottom  layer 
of  this  milk. 

The  amount  of  mixing  necessary  to  evenly  distribute 
the  constituents  of  milk  throughout  its  mass  may  be  as- 
certained by  adding  a  few  drops  of  cheese  color  to  a 
quart  of  milk.  The  yellow  streaks  through  the  milk 
will  be  noticed  until  it  has  been  poured  several  times 
from  one  vessel  to  another,  when  the  milk  will  have  a 
uniform  pale  yellow  color.  Stirring  with  a  stick  or  a 
dipper  will  not  produce  an  even  mixture  so  quickly  or 
so  completely  as  pouring  the  milk  a  few  times  from  one 
vessel  to  another.  In  sampling  milk  for  testing  it 
should  always  be  mixed  just  before  the  milk  is 
measured  into  the  bottle ;  if  several  tests  are  made  of  a 
sample,  the  milk  should  be  mixed  before  each  sampling. 


24  Testing  Milk  and  Its  Products. 

30.  Partially  churned  milk.  A  second  difficulty 
sometimes  met  with  in  sampling  whole  milk  arises  from 
the  fact  that  a  part  of  the  butter  fat  may  be  separated 
in  the  form  of  small  butter  granules,  by  too  zealous  mix- 
ing or  by  reckless  shaking  in  preparing  the  sample  for 
testing.  This  will  happen  most  readily  in  case  of  milk 
from  fresh  cows  or  of  milk  containing  exceptionally 
large  fat  globules.  When  some  of  the  butter  granules 
are  thus  churned  out,  they  quickly  rise  to  the  surface  of 
the  milk  after  pouring  and  cannot  again  be  incorporated 
in  the  milk  by  simple  mixing;  it  is,  therefore  impossi- 
ble to  obtain  a  fair  sample  of  such  milk  for  testing 
without  taking  special  precautions  which  will  be  ex- 
plained in  the  following.  The  granules  of  butter  may 
be  so  small  as  to  pass  into  the  pipette  with  the  milk  and 
the  quantity  measured  thus  contain  a  fair  proportion 
of  them,  but  they  will  be  found  sticking  to  the  inside 
of  the  pipette  when  this  is  emptied,  and  thus  fail  to  be 
carried  into  the  tost  bottle  with  the  milk. 

A  similar  partial  churning  of  the  milk  will  sometimes 
take  place  in  the  transportation  cans.  When  such  milk 
is  received  at  the  factory,  the  butter  granules  are  caught 
by  the  strainer  cloth  through  which  the  milk  is  poured, 
and.  are  thus  lost  both  to  the  factory  and  to  the  farmer. 
This  separated  fat  cannot  be  added  to  the  cream  or  to 
the  granular  butter,  without  running  the  risk  of  mak- 
ing mottled  butter,  and  it  will  not  enter  into  the  sam- 
ple of  milk  taken  for  testing  purposes. 

When  milk  samples  are  sent  by  mail  or  express  in 
small  bottles,  or  carried  to  the  place  of  testing,  they 
often  arrive  with  lumps  of  butter  floating  in  the  milk 
or  sticking  to  the  glass.  This  churning  of  the  milk  can 


Sampling  Milk.  25 

be  easily  prevented  by  completely  filling  the  bottle  or 
the  can.  If  there  is  no  space  left  for  the  milk  in  which  to 
splash  around,  the  fat  will  not  be  churned  out  in  transit. 

31.  Approximately  accurate  results  may  generally  be 
obtained  with  a  partially  churned  sample  of  milk,  if  a 
teaspoonful  of  ether  be  added  to  it.  After  adding  the 
ether,  cork  the  bottle  and  shake  it  until  the  lumps  of 
butter  are  dissolved.  This  ether  solution  of  the  butter 
will  mix  with  the  milk  and  from  the  mixture  a  fairly 
satisfactory  sample  may  generally  be  taken.  The  dilu- 
tion of  milk  by  the  ether  introduces  an  error  in  the 
testing,  and  only  the  smallest  quantity  of  ether  neces- 
sary to  dissolve  the  lumps  of  butter  should  be  used.  If 
desired,  a  definite  quantity  of  ether,  say  five  per  cent 
of  the  volume  of  the  sample  of  milk  to  be  tested,  may 
be  added;  in  such  cases  the  result  of  the  test  must  be 
increased  by  the  per  cent,  of  ether  added. 

EXAMPLE. — To  a  4-oz.  sample  (120  ce.)  of  partially  churned 
milk,  5  per  cent.,  or  6  cc.  of  common  ether  are  added;  the  mix- 
ture gave  an  average  test  of  4.2  per  cent.  The  test  must  be  in- 
creased by  J^Q  X4.2=.21  per  cent.,  and  the  original  milk  there- 
fore contained  4.2 +.21=4.41  per  cent,  of  fat. 

Milk  containing  ether  must  be  mixed  cautiously  with 
acid  in  making  a  test,  so  as  to  avoid  a  loss  of  the  contents 
of  the  bottle  by  the  sudden  boiling  of  the  ether  due  to 
the  heat  evolved  in  mixing  the  milk  and  the  acid. 

Instead  of  adding  ether  to  partially  churned  sam- 
ples, the  milk  may  be  heated  to  about  110°  F.  for  a 
few  minutes,  so  as  to  melt  the  butter  granules;  the 
sample  is  now  shaken  vigorously  until  a  uniform  mix- 
ture of  milk  and  melted  butter  is  obtained,  and  a  pi 
petteful  is  then  quickly  drawn  from  the  sample. 


26  Testing  Milk  and  Its  Products. 

$2.  Sampling  sour  milk.  When  milk  becomes  sour, 
the  casein  is  coagulated  and  the  mechanical  condition  of 
the  milk  thereby  changed  so  as  to  render  difficult  a  cor- 
rect sampling.  The  butter  fat  is  not,  however,  changed 
in  the  process  of  souring;  this  has  been  shown  by  one 
of  us,  among  others,  in  a  series  of  tests  which  were 
measured  from  one  sample  of  sweet  milk  into  six  test 
bottles.  A  test  of  the  milk  in  one  of  these  test  bottles 
was  made  every  month  for  six  months,  and  approxi- 
mately the  same  amount  of  fat  was  obtained  in  the 
tests  throughout  the  series,  as  was  found  originally  in 
the  milk  when  tested  in  a  sweet  condition.1  If  the  milk 
is  in  condition  to  be  sampled,  souring  does  not  there- 
fore interfere  with  its  being  tested  by  the  Babcock  test 
or  with  the  accuracy  of  the  results  obtained. 

In  order  to  facilitate  the  sampling  of  sour  or  lop 
pered  milk,  some  chemical  may  be  added  which  will  re- 
dissolve  the  coagulated  casein  and  produce  a  uniform 
mixture  that  can  be  readily  measured  with  a  pipette. 
Any  alkali  (powdered  potash  or  soda,  or  liquid  ammo- 
nia) will  produce  this  effect.  Only  a  very  small  quan- 
tity of  powdered  alkali  is  necessary  for  this  purpose. 
The  complete  action  of  the  alkali  on  sour  milk  requires 
a  little  time,  and  the  operator  should  not  try  to  hasten 
the  solution  by  adding  too  much  alkali.  An  excess  of 
alkali  will  often  cause  such  a  violent  action  of  the  sul- 
furic  acid  on  the  milk  to  which  the  acid  is  added  (on 
account  of  the  heat  generated  or  the  presence  of  car- 

1  See  Hoard's  Dairyman,  April  8,  1892.  The  same  holds  true  for 
cream,  as  shown  by  Winton  (U.  S.  Dept.  Agr.,  Div.  of  Chemistry,  bull. 
43,  p.  112).  As  to  length  of  time  Babcock  tests  will  keep,  see  Vt 
exp.  sta.,  bull.  lOfi. 


Testing  Milk  and  Its  Products.  27 

bonates  in  the  alkali)  that  the  mixture  will  be  thrown 
out  of  the  neck  of  the  test  bottle  when  this  is  shaken  in 
mixing  the  milk  and  the  acid  (37).  When  powdered 
alkali  is  added  to  the  milk,  it  should  be  allowed  to 
stand  for  a  while,  with  frequent  shaking,  until  the  curd 
is  all  dissolved  and  an  even  translucent  liquid  is  ob- 
tained. Such  milk  may  become  dark-colored  by  the  ac- 
tion of  the  alkali,  but  this  color  does  not  interfere  with 
the  accuracy  of  the  test. 

Instead  of  powdered  soda  or  potash,  these  substances 
dissolved  in  water  (soda  or  potash  lye),  or  strong  am- 
monia, may  be  used  for  the  purpose  of  dissolving  the 
coagulated  casein  in  sour  milk.  In  this  case,  a  definite 
proportion  of  alkali  solution  must  be  taken,  however,  5 
per  cent,  of  the  volume  of  milk  being  usually  sufficient, 
and  the  results  obtained  are  increased  accordingly. 

33.  Sampling  frozen  milk.  When  milk  freezes,  it 
separates  into  two  distinct  portions:  Milk  crystals, 
largely  made  up  of  water,  with  a  small  admixture  of  fat 
and  other  solids,  and  a  liquid  portion,  containing  nearly 
all  the  solids  of  the  milk.  In  sampling  frozen  milk  it 
is  therefore  essential  that  the  liquid  and  the  frozen  part 
be  warmed  and  thoroughly  mixed  by  pouring  gently 
back  and  forth  from  one  vessel  into  another;  the  sam- 
ple is  then  taken  and  the  test  proceeded  with  in  the 
ordinary  manner  (36). 

Questions. 

1.  What   precautions  must  be  taken   in   sampling  milkf     Give 
reasons. 

2.  How  can  a  fair  sample  be  taken  of   (a)    partially  churned 
milk,  (b)  sour  milk,  (c)  frozen  milkf 

3.  If  15  cc.  of  ammonia  are  added  to  500  cc.  of  sour  milk, 
and  a  test  of  3.45  obtained,  what  is  the  correct  test  of  the  milkT 


CHAPTER  III. 


THE  BABCOCK  TEST. 

34.  The  Babcock  test  is  based  on  the  fact  that  strong 
sulfuric  acid  will  dissolve  all  non-fatty  solid  constitu- 
ents of  milk  and 
other  dairy  products, 
and  thus  enable  the 
fat  to  separate  on 
standing.  To  effect  a 
speedy  and  complete 
separation  of  the  fat, 
the  bottles  holding 
the  mixture  of  niilk 
and  acid  are  placed 
in  a  centrifugal  ma- 
chine,  a  so-called 
tester,  and  whirled 
for  four  minutes ;  hot 
water  is  then  added 
so  as  to  bring  the 
liquid  fat  into  the 
graduated  neck  of 
the  test  bottles,  and 
after  a  repeated 

FIG.  4.     The  first  Babcock  tester  made.      whirling)     the     length 

of  the  column  of  fat  is  read  off,  showing  the  per  cent, 
of  fat  contained  in  the  sample  tested. 


The  Babcock  Test.  29 

Sulfuric  acid  is  preferable  to  other  mineral  acids  for 
the  purpose  mentioned,  on  account  of  its  affinity  to 
water ;  when  mixed  with  milk,  the  mixture  heats  greatly, 
thus  keeping  the  fat  liquid  without  the  application  of 
artificial  heat  and  rendering  possible  a  distinct  reading 
of  the  column  of  fat  brought  into  the  neck  of  the  test 
bottles. 

So  far  as  is  known,  any  kind  of  milk  can  be  tested 
by  the  Babcock  test.  Breed,  period  of  lactation,  qual- 
ity or  age  of  the  milk  are  of  no  importance  in  using  this 
method,  so  long  as  a  fair  sample  of  milk  can  be  secured. 
In  cases  of  samples  of  milk  or  other  dairy  products 
rich  in  solids  it  requires  a  little  more  effort  to  obtain  a 
thorough  mixture  with  the  acid  than  with  dairy  prod- 
ucts low  in  solids,  like  skim  milk  or  whey,  which  may 
be  readily  mixed  with  the  acid.  ^*- 


A.— DIRECTIONS  FOR  MAKING  THE  TEST. 

35.  The  various  steps  in  the    manipulation  of    the 
Babcock  test  are  discussed  in  the  following  pages;  at- 
tention is  drawn  to  the  difficulties  which  the  beginner 
and  others  may  encounter  in  the  use  of  the  test,  and 
the  necessary  precautions  to  be  observed  in  order  to 
obtain  accurate  and  satisfactory  results  are  explained 
in  detail.     The  effort  has  been  to  treat  the  subject  ex- 
haustively and  from  a  practical  point  of  view,  so  that 
persons  as  yet  unfamiliar  with  the  test  may  turn  to 
the  pages  of   this  book    for  help   in   difficulties   which 
they  may  meet  with. 

36.  Sampling.    The  sample  to  be  tested  is  first  mixed 
by  pouring  the  milk  from  one  vessel  to  another  two  or 


30  Testing  Milk  and  Its  Products. 

three  times,  so  that  every  portion  thereof  will 
contain  a  uniform  amount  of  butter  fat  (29). 
The  measuring  pipette  (fig.  6),  which  has  a 
capacity  of  17.6  cubic  centimeters,1  is  filled  with 
the  milk  immediately  after  the 
mixing  is  completed,  by  suck- 
ing the  milk  into  it  until  this 
rises  a  little  above  the  mark 
around  the  stem  of  the  pipette ; 
the  forefinger  is  then  quickly 
placed  over  the  end  of  the  pi- 
pjstte  before  the  milk  runs  down 
below  the  mark.  By  slightly 
releasing  the  pressure  of  the 
finger  on  the  end  of  the  pipette, 
the  milk  is  now  allowed  to  run 
down  until  it  just  reaches  the 
mark  on  the  stem ;  the  quantity 
of  milk  contained  in  the  pi- 
pette will  then,  if  this  is  cor- 
rectly made,  be  exactly  17.6  cc. 
The  finger  should  be  fairly  dry 
in  measuring  out  the  milk  so 
that  the  delivery  of  milk  may 
be  readily  checked  by  gentle 
pressure  on  the  upper  end  of 
the  pipette. 

The   point  of  the   pipette  is 

.S.Babcockmllk11™    P1&Ced    in    the    Deck    °f    9         Fio.  6 

test  bottle.        Babcock    test    bottle    (fig.    5),   17p6etctce  p1' 

See  p.  45,  foot  note. 


\ 


The  Babcock  Test. 


31 


this    way,    there    is 


and  the  milk  is  allowed  to  flow  slowly  down  the  inside 
of  the  neck.  Care  must  be  taken  that  none  of  the  milk 
measured  out  is  lost  in  this  transfer.  The  portion  of 
the  milk  remaining  in  the  point  of  the  pipette  is  blown 
into  the  test  bottle. 
The  best  and  saf- 
est manner  of  hold- 
ing the  bottle  and  the 
pipette  in  this  trans- 
fer is  shown  in  fig. 
7.  Fig.  8  shows  a 
position  which  should 
be  avoided,  since  by 
holding  the  bottle  in 

danger  that  some  of  the 
milk  may  completely  fill 
the  neck  of  the  bottle, 
and  as  a  result,  flow 
over  the  top  of  the  neck. 
Pipettes,  the  lower 
part  of  which  slip  read- 
ily into  the  necks  of  the 
test  bottles,  may  be 
emptied  by  lowering 
the  pipette  into  the 
neck  of  the  bottle  till 
it  rests  on  its  rim,  when 

FIG.  7.     The  right  way  of  emptying  the    milk    is    allowed    to 
pipette  into  test  bottle. 

run  into  the  test  bottle. 

37-  Adding  acid.     The  acid  cylinder   (fig.  9)    hold- 
ing 17.5  cc.,  is  filled  to  the  mark  with  sulfuric  acid  01 


32 


Testing  Milk  and  Its  Products. 


a  specific  gravity  of  1.82-1.83.  This  amount  of  acid  is 
carefully  poured  into  the  test  bottle  containing  the  milk. 
In  adding  the  acid,  the  test  bottle  is  conveniently  held 
at  an  angle  (see  fig.  7),  so  that  the  acid  will  run  down 
the  wall  of  the  bottle  and 
not  run  in  a  small  stream  into 
the  center  of  the  milk,  the 
bottle  being  slowly  turned 
around  and  the  neck  thus 
cleared  of  adhering  milk.  By 
pouring  the  acid  into  the 
middle  of  the  test  bottle, 
there  is  also  a  danger  of  com- 
pletely filling  this  with  acid, 
in  which  case  the  plug  of 
acid  formed  will  be  pushed 
over  the  edge  of  the  neck  by 
the  expansion  of  the  air  in 
the  bottle,  and  may  be  spilled 
on  the  hands  of  the  operator. 
The  milk  and  the  acid  in 
the  test  bottle  should  be  in 
two  distinct  layers,  without 
much  of  a  black 
band  of  partially 
mixed  liquids  be- 
tween them.  Such  FlG>  8-  ^  wrong  way  of  emptying  pipette 

a  dark  layer  is  of- 
ten followed  by  an  indistinct  separation  of  the  fat  in 
the  final  reading.  The  cause  of  this  may  be  that  a  par- 
tial mixture  of  acid  and  milk  before  the  acid  is  diluted 


The  Babcock  Test. 


33 


with  the  water  of  the  milk  will  bring  about  too  strong 
an  action  of  the  acid  on  this  small  portion  of  the  milk, 
and  thus  char  the  fat  contained  therein.  The  appear- 
ance of  black  flocculent  matter  in  or  below  the  col- 
umn of  fat  which  generally  results,  in 
either  case  renders  a  correct  measurement 
difficult  and  at  times  even  impossible;  if 
the  black  specks  occur  in  the  fat  column 
itself,  the  readings  are  apt  to  be  too  high; 
if  below  it,  the  difficulty  comes  in  decid- 
ing where  the  column  of  fat  begins. 

38.  Mixing  milk  and  acid.  After  add- 
ing the  acid,  this  is  carefully  mixed  with 
the  milk  by  giving  the  test  bottle  a  rotary 
motion.  In  doing  this,  care  should  be 

FIG.  9.    17.5  cc. 

taken  that  the  liquid  is  not  shaken  into  acid  cylinder, 
the  neck  of  the  test  bottle.  When  once  begun,  the  mix- 
ing should  be  continued  until  completed;  a  partial  and 
interrupted  mixing  of  the  liquids  will  often  cause  more 
or  less  black  material  to  separate  with  the  fat  when  the 
test  is  finished.  Clots  of  curd  which  separate  at  first 
by  the  action  of  the  acid  on  the  milk,  must  be  entirely 
dissolved  by  continued  and  careful  shaking  of  the  bot- 
tle. Beginners  sometimes  fail  to  mix  thoroughly  the 
milk  and  the  acid  in  the  test  bottle.  As  the  acid  is 
much  heavier  than  the  milk  a  thin  layer  of  it  is  apt  to 
be  left  unnoticed  at  the  bottom  of  the  bottle,  unless  this 
is  vigorously  shaken  toward  the  end  of  the  operation. 

The  mixture  becomes  hot  by  the  action  of  the  acid  on 
the  water  in  the  milk  and  turns  dark  colored,  owing  to 
the  effect  of  the  strong  sulfurie  acid  on  the  nitrogenous 
constituents  and  the  sugar  in  the  milk. 


34  Testing  MUk  and  Its  Products. 

Colostrum  milk  or  milk  from  fresh  cows  will  form  a 
violet  colored  mixture  with  the  acid,  due  to  the  action 
of  the  latter  on  the  albumen  present  in  such  milk  in 
considerable  quantities  (23). 

When  milk  samples  are  preserved  by  means  of  potas- 
sium bichromate  (190),  and  so  much  of  this  material  has 
been  added  that  the  milk  has  a  dark  yellow  or  reddish 
color,  the  mixture  of  milk  and  acid  will  turn  greenish 
black,  and  a  complete  solution  is  rendered  extremely 
difficult  on  account  of  the  toughening  effect  of  the  bi- 
chromate on  the  precipitated  casein.  This  difficulty  is 
still  more  pronounced  with  milk  preserved  with  form- 
aldehyd. 

39.  Whirling  bottles.  After  the  milk  and  the  acid 
have  been  thoroughly  mixed,  the  test  bottle  is  at  once 
placed  in  the  centrifugal  machine  or  tester  and  whirled 
for  four  or  five  minutes  at  a  speed  of  600  to  1200  revo- 
lutions per  minute,  according  to  the  diameter  of  the 
tester  (66).  It  is  not  absolutely  necessary  to  whirl  the 
test  bottles  in  the  centrifuge  as  soon  as  the  milk  and 
the  acid  are  mixed,  although  this  method  of  procedure 
is  much  to  be  preferred ;  they  may  be  left  in  this  condi- 
tion for  any  reasonable  length  of  time  (24  hours,  if 
necessary)  without  the  test  being  spoiled.  If  left  until 
the  mixture  becomes  cold,  the  bottles  should,  however, 
be  placed  in  warm  water  (of  about  160°  F.)  for  about 
fifteen  minutes  before  whirling. 

Four  minutes  at  full  speed  is  sufficient  for  the  first 
whirling  of  the  test  bottles  in  the  centrifuge;  this  will 
bring  all  fat  to  the  surface  of  the  liquid  in  the  bottle. 


The  Babcock  Test. 


35 


40.  Adding  water.  Hot  water  is  now  added  by  means 
of  a  pipette  or  some  special  device  (10  in  fig.  58),  1  until 
the  bottles  are  filled  to  near  the  scale  on  the  neck  (80). 
The  bottles  are  whirled  again  at  full  speed  for  one  min- 
ute, and  hot  water  added  a  second  time,  until  the  lower 
part  of  the  column  of  fat  comes  within  the  scale  on  the 
neck  of  the  test  bottle,  preferably  to  the  1  or  2  per 
cent,  mark,  so  as  to  allow  for  the  sinking  of  the  column 
of  fat,  due  to  the  gradual  cooling  of  the  contents  of  the 
bottle.  By  dropping  the  water  directly  on  the  fat  in 
the  second  filling,  the  column  of  fat  will  be  washed  free 
from  light  flocculent  matter,  which  might  otherwise  be 
entangled  therein  and  render  the 
reading  uncertain  or  too  high.  A 
final  whirling  for  one  or  two  min- 
utes completes  the  separation  of 
j  the  fat. 

41.  Measuring  the  fat.  The 
amount  of  fat  in  the  neck  of  the 
bottle  is  measured  by  the  scale  or 
graduations  on  the  neck.  Each 
division  of  the  scale  represents 
two-tenths  of  one  per  cent  of  fat2 
and  the  space  filled  by  the  fat 
shows  the  per  cent,  of  butter  fat 
contained  in  the  sample  tested. 
FIG.  10.  Measuring  the  The  fat  is  measured  from  the 
Babcock  "test*  "botXe.  &  lower  line  of  separation  between 
the  fat  and  the  water,  to  the  top  of  the  fat  column,  at 
the  point  6,  shown  in  the  figure,  the  reading  being  thus 
taken  from  a  to  6,  and  not  to  c  or  to  fl.  Comparative 


See  under  204. 
2  One-tenth  of  one  per  cent,  in  rase  of  8  per  cent,  bottles. 


36  Testing  milk  and  its  Products. 

gravimetric  analyses  have  shown  that  the  readings  ob- 
tained in  this  manner  give  correct  results.  While  the 
lower  line  of  the  fat  column  is  nearly  straight,  the  upper 
one  is  curved,  and  errors  in  the  reading  are  therefore 
easily  made,  unless  the  preceding  rule  is  observed. 

Results  with  8%  bottles  (44a)  agree  well  with  those 
obtained  with  the  10%  bottles,  when  care  is  taken  to 
read  the  fat  column  to  the  extreme  top  of  the  menis- 
cus. This  appears  especially  thin  in  the  former  bottles 
and  cannot  be  seen  quite  as  readily  as  in  the  10% 
bottles. 

The  fat  obtained  should  form  a  clear  yellowish  liquid 
distinctly  separated  from  the  acid  solution  beneath  it. 
There  should  be  no  black  or  white  sediment  in  or  below 
the  column  of  fat,  and  no  bubbles  or  foam  on  its  sur- 
face. The  bottles  must  be  kept  warm  until  the  read- 
ings are  made,  so  that  the  column  of  fat  will  have  a 
sharply  defined  upper  and  lower  meniscus.  When  the 
testing  is  done  in  a  cold  room,  it  is  a  good  plan  to  place 
the  bottles  in  a  pail  with  water  of  140°  F.  be- 
fore readings  are  made.  The.  readings  should  always 
be  made  when  the  fat  has  a  temperature  of  about  140° 
P. ;  too  low  results  will  be  obtained  if  the  fat  is  allowed 
to  cool  below  120°  P.,  and  too  high  if  readings  are 
taken  above  150°.  The  fat  separated  in  the  Babcock 
test  solidifies  at  about  100°  P.  If  the  fat  is  partly  sol- 
idified, it  is  impossible  to  make  an  accurate  reading.1 

1  The  effect  of  differences  in  the  temperature  of  the  fat  on  the  read- 
ings obtained  will  be  seen  from  the  following:  If  110  and  150°  F.  be 
taken  as  the  extreme  temperatures  at  which  readings  can  be  mado, 
this  difference  of  40"  P.  (22.3°  C.)  would  mane  a  difference  in  the  vol- 
ume of  the  fat  column  obtained  in  the  case  of  10  per  cent,  milk  of 
.  00064  x2x22.3=.028544  cc.,  or  .14  per  cent.,  .00064  being  the  expansion 
coefficient  of  pure  butter  fat  per  dojiree  Centigrade  between  50  and  100° 


The  Babcock  Test.  37 

42.  Readings  of  tests  of  milk  made  in  steam  turbine 
testers  with  tightly  closed  covers  which  prevent  the  free 
escape  of  exhaust  steam  (71),  will  come  .2  to  .3  per  cent. 
too  high  if  the  temperature  of  the  fat  is  allowed  to  rise 
to  that  of  the  exhaust  steam  during  the  process  of  whirl- 
ing.   In  such  cases  the  test  bottles  must  be  allowed  to 
cool  to  about  140°,  by  placing  them  in  water  of  this 
temperature  for  a  few  minutes,   before   readings  are 
taken.1 

A  pair  of  dividers  will  be  found  convenient  for  meas- 
uring the  fat,  and  the  liability  of  error  in  reading  is 
decreased  by  their  use.  The  points  of  the  dividers  are 
placed  at  the  upper  and  lower  limits  of  the  fat  column 
(from  a  to  b  in  fig.  10).  The  dividers  are  now  lowered, 
one  point  being  placed  at  the  zero  mark  of  the  scale, 
and  the  mark  at  which  the  other  point  touches  the  scale 
will  show  the  per  cent,  of  fat  in  the  sample  tested. 
The  dividers  must  be  tight  in  the  joint  to  be  of  use  for 
this  purpose. 

B.— DISCUSSION  OF  THE  DETAILS  OF  THE 
BABCOCK  TEST. 

43.  The  main  points  to  be  observed  as  to  apparatus 
and  testing  materials  in  order  to  obtain  correct  and 
satisfactory  results  by  this  test  will  now  be  considered, 
and  such  suggestions   and  help   offered  as  have  been 
found  needful  from  past  experience  with  a  great  variety 
of  samples  of  milk,  apparatus,  and  accessories. 


C.  (Zvne,  Analyse  des  Beurres,  I,  87),  and  2,  the  volume  of  the  fat  in 
cc.  contained  in  17.6  cc.  of  10  per  cent.  milk.     On  5  per  cent,  milk  this 
extreme  difference  would  therefore  be  about  .07,   or  nearly  .1   of  1%. 
1  See  Wis,  Expt.  Sta.  rep.,  XVII,  p.  76. 


38  Testing  Milk  and  Its  Products. 

1.— GLASSWARE. 

44.  Test  bottles.  The  test  bottles  should  have  a  ca- 
pacity of  about  50  cc.,  or  less  than  two  ounces;  they 
should  be  made  of  well-annealed  glass  that  will  stand 
sudden  changes  of  temperature  without  breaking,  and 
should  be  sufficiently  heavy  to  withstand  the  maximum 
centrifugal  force  to  which  they  are  likely  to  be  sub- 
jected in  making  tests.  This  force  may,  on  the  average, 
be  not  far  from  30.65  Ibs.  (see  66),  which  is  the  pres- 
sure exerted  in  whirling  the  bottles  filled  with  milk  and 
acid  in  a  centrifugal  machine  of  18  inches  diameter  at 
a  speed  of  800  revolutions  per  minute. 

When  17.6  cc.,  or  18  grams  of  milk  (48),  are  meas- 
ured into  the  Babcock  test  bottle,  the  scale  on  the  neck 
of  the  bottles  will  show  directly  the  per  cent,  of  fat 
found  in  the  milk.  The  scale  is  graduated  from  0  to 
10  per  cent.  10  per  cent,  of  18  grams  is  1.8  grams.  As 
the  specific  gravity  of  pure  butter  fat  (i.  e.,  its  weight 
compared  with  that  of  an  equal  volume  of  pure  water) 
at  the  temperature  at  which  the  readings  are  made 
(about  140°  P.),  is  0.9,  then  1.8  grams  of  fat  will  oc- 
cupy a  volume  of  iv8=2  cubic  centimeters.  The  space 
between  the  0  and  10  per  cent,  marks  on  the  necks  of 
the  test  bottles  must  therefore  hold  exactly  2  cubic  cen- 
timeters. The  scale  is  divided  into  10  equal  parts,  each 
part  representing  one  per  cent.,  and  each  of  these  is 
again  sub-divided  into  five  equal  parts.  Each  one  of  the 
latter  divisions  therefore  represents  two-tenths  of  one  per 
cent,  of  fat  when  17.6  cc.  of  milk  is  measured  out.  The 
small  divisions  are  sufficiently  far  apart  in  most  Bab- 
cock  test  bottles  to  make  possible  the  estimation  of  one- 


The  Babcock  Test.  39 

tenth,  or  even  five-hundredths,  of  one  per  cent,  of  fat 
in  the  samples  tested. 

In  the  best  kinds  of  Babcock  bottles  the  per  cent, 
marks  are  complete  circles  and  the  half  per  cent, 
marks  are  semi-circles.  This  greatly  aids  in  making 
correct  readings. 

As  the  necks  of  Babcock  test  bottles  vary  in  diame- 
ter, each  separate  bottle  must  be  calibrated  by  the  manu- 
facturers ;  the  length  of  the  scale  is  not,  for  the  reasons 
given,  apt  to  be  the  same  in  different  bottles. 

If  the  figures  and  lines  of  the  scale  become  indistinct 
by  use,  the  black  color  may  be  restored  by  rubbing  a 
soft  pencil  over  the  scale,  or  by  the  use  of  a  piece  of 
burnt  cork  after  the  scale  has  been  rubbed  with  a  little 
tallow.  On  wiping  the  neck  with  a  cloth  or  a  piece  of 
paper  the  black  color  will  show  in  the  etchings  of  the 
glass,  making  these  plainly  visible. 

Special  forms  of  test  bottles  used  in  testing  cream 
and  skim  milk  are  described  under  the  heads  of  cream 
and  skim-milk  testing  (89,  90,  99). 

443.  Eight-per-cent.  bottles.  Milk  test  bottles  with 
scale  graduated  from  0  to  8  per  cent,  have  come  into 
general  use  of  late  years,  having  been  adopted  in  1911 
by  the  National  Dairy  Instructors'  Association  as 
"standard."  The  specifications  for  this  bottle  and 
other  Babcock  glassware  are  given  in  par.  307. 

45.  Marking  test  bottles.  Test  bottles  can  now  be 
bought  with  a  small  band  or  portion  of  their  neck  or 
body  ground  or  "frosted,"  for  numbering  the  bottles 
with  a  lead  pencil.  Bottles  without  this  ground  label 
can  be  roughened  at  any  convenient  spot  by  using  a  wet 
fine  file  to  roughen  the  smooth  surface  of  the  glass. 


40  Testing  Milk  and  Its  Products. 

There  is  this  objection  to  the  latter  method  that,  unless 
carefully  done,  it  is  apt  to  weaken  the  bottles  so  that 
they  will  easily  break,  and  to  both  methods,  that  the 
lead  pencil  marks  made  on  such  ground  labels  may  be 
effaced  during  the  test  if  the  bottles  are  not  carefully 
handled.  Small  strips  of  tin  or  copper  with  a  number 
stamped  thereon  are  sometimes  attached  as-  a  collar 
around  the  necks  of  the  bottles.  They  are,  however, 
easily  lost,  especially  when  the  top  of  the  bottle  is 
slightly  broken,  or  at  any  rate,  are  soon  corroded  so 
that  the  numbers  can  only  be  seen  with  difficulty. 

The  best  and  most  permanent  label  for  test  bottles  is 
made  by  scratching  a  number  with  a  marking  diamond 
on  the  glass  di- 
rectly above  the 
scale  on  the  neck 
of  the  bottles  or 
by  grinding  a 
number  on  the 
bottle  itself.  In 
ordering  an  out- 
fit, or  test  bottles 
alone,  the  oper-  = 
ator  may  specify 

that     the     bottles  FIG.  12.     Waste-acid  Jar. 

are  to  be  marked  1  to  24,  or  as  many  as  are  bought, 
and  the  dealer  may  then  put  the  numbers  on  with  a 
marking  diamond. 

A  careful  record  should  be  kept  of  the  number  of  the 
bottle  into  which  each  particular  sample  of  milk  is 
measured.  Mistakes  often  happen  when  the  operator 


The  Babcock  Test. 


41 


trusts  to  his  memory  for  locating  the  different  bottles 
in  which  tests  are  made  at  the  same  time. 

46.  Cleaning  test  bottles.     The  fat  in  the  neck  of 
the  test  bottles  must  be  liquid  when  these  are  cleaned. 


FIG.  13.  Apparatus  for  cleaning  test  bottles.  A,  apparatus  in  posi 
tion ;  the  water  flows  from  the  reservoir  through  the  iron  pipe  6  into 
the  inverted  test  bottle  d  through  the  brass  tube  c,  screwed  into  the 
iron  pipe.  B  shows  construction  of  the  rubber  support  on  which  the 
test  bottles  rest ;  /,  sink. 

In  emptying  the  acid  the  bottle  should  be  shaken  in 
order  to  remove  the  white  residue  of  sulfate  of  lime, 
etc.,  from  the  bottom;  if  the  acid  is  allowed  to  drain 
out  of  the  bottle  without  shaking  it,  this  residue  will 


42  Testing  Jd.Hk  and  Its  Products. 

be  found  to  stick  very  tenaciously  to  the  bottom  of  the 
bottle  in  the  subsequent  cleaning  with  water. 

A  convenient  method  of  emptying  test  bottles  is  shown 
in  the  illustration  (fig.  12).  After  reading  the  fat  col- 
umn, the  bottles  are  placed  neck  down,  in  the  half-inch 
holes  of  the  board  cover  of  a  five-gallon  stoneware  jar. 
An  occasional  shaking  while  the  liquid  is  running  from 
the  bottles  will  rinse  off  the  precipitate  of  sulfate  of 
lime.  A  thorough  rinsing  with  boiling  hot  water  is 
generally  sufficient  to  remove  all  grease  and  dirt,  as 
well  as  acid  solution  from  the  inside  of  the  bottles. 
The  apparatus  shown  in  fig.  13  will  be  found  convenient 
for  this  purpose.  After  the  bottles  have  been  rinsed  a 
second  time,  they  may  be  placed  in  an  inverted  posi- 
tion to  drain,  on  a  galvanized  iron  rack,  as  shown  in 
fig.  14,  where  they  are  kept  until  needed.  The  outside 
L .  _  r~  rv-  ~~  °^  ^e  bottles  should 

occasionally  be  wiped 
clean  and  dry. 

47.  The  amount  of 
unseen  fat  that  clings 
to  test  bottles  used 

FIG.  14.     Draining  rack  for  test  bottles.       . 

for    testing    milk    or 

cream,  is  generally  not  sufficient  to  be  noticed  in  test- 
ing whole  milk,  but  it  plays  an  important  part  in  test- 
ing samples  of  separator  skim  milk.  It  may  be  readily 
brought  to  light  by  making  a  blank  test  with  clean 
water  in  bottles  used  for  testing  ordinary  milk,  which 
have  been  cleaned  by  simply  draining  the  contents  and 
rinsing  once  or  twice  with  hot  water;  at  the  conclusion 
of  the  test  the  operator  will  generally  find  that  a  few 


The  Babcock  Test. 


43 


drops  of  fat  will  collect  in  the  neck  of  the  bottles,  some- 
times enough  to  condemn  a  separator. 

Boiling  hot  water  will  generally  clean  the  grease  from 
glassware  for  a  time,  but  all  test  bottles  should,  in  ad- 
dition, be  given  an  occasional  bath  in  some  weak  alkali 
or  other  grease-dissolving  solution.  Persons  doing  con- 
siderable milk  testing  will  find  it  of  advantage  to  pro- 
vide themselves  with  a  small  copper  tank,  fig.  15, 
which  can  be  filled  with  a  weak  alkali-solution.  After 
having  been  rinsed  with  hot  water,  the  test  bottles  are 
placed  in  the  hot  solution  in  the  tank,  where  they  may 
be  left  completely  covered  with  the  liquid.  If  the  tank 
is  provided  with  a  small  faucet  at  the  bottom,  the  liquid 
can  be  drawn  off  when  the  test  bottles  are  wanted.  A 
tablespoonful  of 
some  cleaning  pow- 
der to  about  two 
gallons  of  water 
will  make  a  very 
satisfactory  solu- 
tion ;  sal  soda, 
Gold  Dust,  Lewis' 
lye  or  Babbitt's 
potash  are  very 
efficient  for  this 
purpose.  The 
cleansing  proper- 
ties of  solutions  of 
any  of  these  sub- 
stances  are  in- 
creased by  warm- 
ing the  liquid.  The  FIQ  15  Tank  for  c]eanlnjr  t<J8t 


44  Testing  Milk  and  Its  Products. 

test  bottles  must  be  rinsed  twice  with  hot  water  aftei 
they  are  taken  from  this  bath. 

An  excellent  cleaning  solution  that  can  be  used  for 
a  long  time,  may  be  made  of  one-half  pound  bichromate 
of  potash  to  one  gallon  of  sulfuric  acid.1 

473.  An  arrangement  for  cleaning  a  number  of  test 
bottles  at  the  same  time  is  shown  in  fig.  16. 2  III  shows 


.  . 

FIG.  16.     A  convenient  device  for  cleaning  test  bottles. 


the  frame  in  which  the  bottles  are  placed,  one  in  each 
socket;  the  metal  plate  E  is  put  over  the  necks  of  the 
bottles  which  pass  through  the  holes  in  it  up  to  the 
shoulder  of  the  bottles.  The  pins  F,  P,  are  then  pushed 
through  holes  in  the  rods  D-D,  and  the  plate  and  bot- 
tles thus  firmly  held  in  the  crate.  When  secured  in 
this  way,  the  frame  full  of  bottles  may  be  placed  in  a 
pail  or  tank  of  hot  water  as  in  I.  They  will  soon  fill 
with  water  and  the  time  of  filling  the  bottles  one  at  a 
time  thus  saved.  When  ready  to  empty  the  bottles,  the 

1  Michels,  Am.  Cheesemaker,  Jan.  1903. 
*  Wisconsin  experiment  station,  bull.  128. 


The  Babcock  Test.  45 

frame  is  reversed  and  placed  in  the  position  shown 
in  II. 

One  or  two  rinsings  in  boiling  hot  water  is  usually 
sufficient  to  effectually  clean  the  bottles,  but  when  they 
have  been  allowed  to  get  greasy  they  can  be  dipped  into 
a  pail  of  hot  dilute  lye;  this  will  saponify  the  grease 
and  after  one  or  two  rinsings  in  clean  hot  water  the 
bottles  will  be  bright  and  clean. 

The  black  stains  that  sometimes  stick  to  the  inside  of 
test  bottles  after  prolonged  use,  can  be  removed  with  a 
little  muriatic  acid,  or  by  means  of  a  small  stiff  brush. 

48.  Pipette.  The  difference  in  the  weights  of  various 
samples  of  normal  milk  generally  falls  within  compara- 
tively narrow  limits ;  if  a  given  volume  of  water  weighs 
one  pound,  the  same  volume  of  the  usual  grades  of  nor- 
mal milk  will  weigh  from  1.029  to  1.033  pounds,  or  on 
the  average,  1.03  Ibs.  18  grams  of  water  measures  18 
cc.1 ;  18  grams  of  milk  will  therefore  take  up  a  smaller 
volume  than  18  cc.,  \iz.,  18  divided  by  1.03,  which  is 
very  nearly  17.5.  This  is  the  quantity  of  milk  taken 
in  the  Babcock  test.  A  certain  amount  of 
milk  will  adhere  to  the  walls  of  the  pi- 
pette when  it  is  emptied,  and  this  thin  film 
has  been  found  to  weigh  about  one-tenth 
of  a  gram ;  consequently  17.6  cc.  has  been 
adopted  as  the  capacity  of  the  pipette  used 
for  delivering  18  grams  of  milk. 

For  convenience  in  measuring  the  milk, 
the  shape  of  the  pipette  is  of  importance. 
The  mark  on  the  stem  should  be  two  inches 
or  more  from  the  upper  end  of  the  pi-  construction. 

1  Cubic  centimeters  (abbreviated:  cc.)  are  the  standard  used  for 
measuring  volume  In  the  metric  system,  similar  to  the  quart  or  pint 


46  Testing  Milk  and  Its  Products. 

pette.  The  lower  part  should  be  small  enough  to  fit 
loosely  into  the  neck  of  the  test  bottle,  and  not  con- 
tracted to  a  fine  hole  at  the  point;  the  point  should  be 
large  enough  to  allow  a  quick  emptying  of  the  pipette 
(fig.  17)  and  not  so  large  that  it  is  difficult  to  use  it. 
An  opening  of  about  %  in.  diameter  will  be  found 
satisfactory. 

49.  Fool  pipettes.  Soon  after  the  Babcock  test  began  to  be 
generally  used  at  creameries  as  a  basis  of  payment  for  the  milk, 
a  creamery  supply  house  put  on  the  market  a  20  cc.  milk-meas- 
uring pipette,  which  was  claimed  to  show  the  exact  butter  value 
of  milk,  instead  of  its  content  of  butter  fat,  as  is  the  case  in 
using  the  ordinary  17.6  cc.  pipette.  A  20  cc.  pipette  will  de- 
liver 2.4  cc.  more  milk  than  a  17.6  cc.  pipette,  (or  13.6  per  cent, 
more),  and  the  results  obtained  by  using  these  pipettes  will, 
therefore,  be  about  13.6  per  cent,  too  high.  In  considering  the 
subject  of  Overrun  (214)  it  is  noted  that  the  excess  of  butter 
yield  over  the  amo'unt  of  fat  contained  in  a  certain  quantity  of 
milk  will  range  from  about  10  to  16  per  cent.,  or  on  the  average, 
about  12  per  cent.  20  cc.  pipettes  may.  therefore,  give  approxi 
mately  the  yield  of  butter  obtained  from  a  quantity  of  milk, 
but  as  will  be  seen,  this  yield  is  variable,  according  to  the  skill 
of  the  butter  maker  and  to  conditions  beyond  his  control;  it  can- 
not therefore  be  used  as  a  standard  in  the  same  manner  as  the 
fat  content  of  milk.  Similar  22  ec.  pipettes  were  also  sent  out. 
These  pipettes  created  a  great  deal  of  confusion  during  the  short 
time  they  were  on  the  market,  and  were  popularly  termed  ' '  fool ' ' 
pipettes.  It  is  not  known  that  such  pipettes  have  been  sold  of 
late  years. 

The  dairy  laws  of  many  states  make  it  a  misdemeanor  to 
use  other  than  17.6  cc.  pipettes  for  measuring  milk  where 
this  is  paid  for  by  the  Babcock  test. 

measure  in  our  ordinary  system  of  measures.  One  quart  is  equal  to  a 
little  less  than  1,000  cubic  centimeters  (1  liter).  In  the  same  way, 
grams  represent  weight,  like  pounds  and  ounces.  One  cc.  of  water  at 
4'  Centigrade  weighs  1  gram  ;  1,000  grams  (=1  kilogram)  are  equal  to 
2.2  Ibs.  Avoirdup.  (See  Appendix  for  Comparisons  of  metric  and 
customary  weights  and  measures.) 


The  Babcock  Test.  47 

50.  Acid  measures.    A  17.5  cc.  glass  cylinder  (fig.  9) 
for  measuring  the  acid  is  generally  included  in  the  out- 
fit, when  a  Babcock  tester  is  bought.    This  cylinder  an- 
swers every  purpose  if  only  occasional  tests  are  made; 
the  acid  is  poured  into  the  cylinder  from  the  acid  bottle 
as  needed,  or  a  quantity  of  acid  sufficient  for  the  num- 
ber of  test  bottles  to  be  whirled  at  a  time,  is  poured 
into  a  small  glass  beaker  provided  with  a  lip,  or  into  a 
small    porcelain    pitcher;    these    may    be    more    easily 
handled  than  the  heavy  acid  bottle  or  jug,  and  the  acid 
measure  is  then  filled  from  such  a  vessel. 

Where  a  considerable  number  of  tests  are  made  regu- 
larly, the  acid  can  be  measured  into  the  test  bottles 
faster  and  with  less  danger  of  spilling,  by  using  some 
one  of  the  many  devices  proposed  for  this  purpose. 
There  is  some  objection  to  nearly  all  of  these  appliances, 
automatic  pipettes,  burettes,  etc.,  although  they  will 
often  give  good  satisfaction  for  a  time  while  new.  Sul- 
furic  acid  is  very  corrosive,  and  operators,  as  a  rule, 
take  but  poor  care  of  such  apparatus,  so  that  it  is  a 
very  difficult  matter  to  design  a  form  which  will  re- 
main in  good  working  order  for  a  long  time.  Auto- 
matic pipettes  attached  to  acid  bottles  or  reservoirs,  to 
prove  satisfactory,  must  be  made  entirely  of  glass,  and 
strong,  of  simple  construction,  tightly  closed  and 
quickly  operated. 

51.  The   Combined   acid  bottle1   answers   these 
requirements  better  than  any  other  device  known  to 
writers  at  the  present  time.  Its  use  is  easily  understood 
(see  fig.  18);  it  gives  good  satisfaction  if  the  hole  in 
the  glass  stop-cock  through  which  the  acid  passes  has 

'Formerly  sold  and  known  as  the  The  Swedish  Acid  Bottle. 


48 


Testing  Milk  and  Its  Products. 


a  diameter  of  at  least  one-eighth  of  an  inch,  as  is  gener- 
ally the  case.  We  have  used  or  inspected  some  half  a 
dozen  other  devices  placed  on 
the  market  by  various  deal- 
ers for  delivering  the  acid, 
but  cannot  recommend  them 
for  use  in  factories  or  outside 
of  chemical  laboratories. 

52.  Instead  of  measuring  out  the 
acid,  Bartlett1  has  suggested  add- 
ing 20  cc.  directly  to  the  milk~  in 
the  test  bottles,  till  the  mixture 
rises  to  a  mark  pn  the  body  of  the 
bottle  at  the  point  where  this  will 
hold  37.5  cc.,  i.  e.,  the  total  volume 
of  milk  and  acid  (83).  This  method 
of  adding  the  acid  is  in  the  line  of 
simplicity,  but  has  not  become  gen- 
erally adopted.  If  the  method  is 
used,  the  marks  should  be  put  on 
by  the  manufacturers,  as  the  oper- 
ator in  attempting  to  do  so  will  be  apt  to  weaken  or  break  the 
bottles. 

CALIBRATION  OF  GLASSWARE. 

53.  Test  Bottles.  The  Babcock  10%  milk  test 
bottles  are  so  constructed  that  the  scale  of  graduation 
on  the  neck  measures  a  volume  of  2  cubic  centimeters, 
between  the  zero  and  the  10  per  cent,  marks  (44).  The 
standards  for  test  bottles  and  other  Babcock  glassware 
adopted  by  the  associationjof  official  agricultural  chem- 
ists of  America  are  given  at  the  close  of  this  book 
(.306).  It  will  be  seen  that  the  limit  of  error  for  test 
bottles  is  one  of  the  smallest  graduations  on  the  scale, 


o.  18.  Acid  measuring  bollle 
the  side  tube  is  made  to 
hold  17.5  cc.  of  acid. 


'Maine   experiment  station,   bull.    31. 


The  Babcock  Test.  49 

or  .2  per  cent.  The  correctness  of  the  graduations  may 
l»e  easily  ascertained  by  one  of  the  following  methods : 
54.  (A.)  Calibration  with  water.  This  may  be  done 
by  means  of  an  accurate  pipette  or  burette,  or  by  weigh- 
ing the  water  that  the  graduated  portion  of  the  neck 
will  hold. 

a,  Measuring  the  water.     Fill  the  test  bottle  with 
water  to  the  zero  mark  on  the  scale;  remove  any  sur- 
plus water  and  dry  the  inside  of  the  neck  with  a  piece 
of  filter  paper  or  clean  blotting  paper;  then  measure 
into  the  bottle  2  cc.  of  water  from  an  accurate  pipette 
or  burette,  divided  to  one-twentieth  of  a  centimeter.   If 
the  graduation  is  correct,  2  cc.  will  fill  the  neck  exactly 
to  the  10  per  cent,  mark  of  the  scale. 

b,  Weighing  the  water.     Fill  the  bottle  with  water 
to  the  zero  mark  of  the  scale  and  remove  any  surplus 
water  in  the  neck,  as  before.    Weigh  the  bottle  with  the 
water  contained  therein.     Now  fill  the  neck  with  water 
to  the  10  per  cent,  mark,  and  weigh  again.    The  differ- 
ence between  these  weights  should  be  2  grams. 

In  all  cases  where  calibrations  are  to  be  made,  the 
test  bottles,  or  other  glassware  to  be  calibrated,  must  be 
thoroughly  cleaned  beforehand  with  strong  sulfuric 
acid  or  soda  lye,  and  washed  repeatedly  with  pure 
water,  and  dried.  Glassware  is  not  clean  unless  water 
will  run  freely  over  its  surface,  without  leaving  any 
adhering  drops. 

55-  (B).  The  Trowbridge  method  of  calibration.1 
An  extremely  simple  and  accurate  method  of  calibrating 
test  bottles  has  been  proposed  by  Mr.  0.  A.  Trowbridge 
of  Columbus,  Wis.  The  capacity  of  the  graduated  por- 

1  Hoard's  Dairyman,  March  8,  1901,  by  DeWitt  Goodrich. 
4 


50.  Testing  Milk  and  Its  Products. 

tion  of  the  neck  of  a  milk  test  bottle  is  measured  with  a 
piece  of  metal  which  is  carefully  filed  to  such  a  size  that 
it  will  displace  exactly  two  cubic  centimeters  of  water. 
He  used  a  thirty-penny  wire  nail,  cutting  off  the  head 
of  the  nail  and  attaching  to  it  a  short  piece  of  fine  wire 
Manufacturers  have  improved  on  this  rather  crude  de- 
vice and  standard  measures  for  calibrating 
test  bottles  can  now  be  bought  of  dairy 
supply  houses  (see  fig.  19). 

When  a  test  bottle  is  to  be  calibrated 
by  this  standard  measure,  it  is  filled  with 
water  to  the  zero  mark  on  the  neck  of  the 
bottle.  The  water  adhering  to  the  neck  is 
carefully  removed  with  a  strip  of  blotting 
paper,  and  the  measure  is  then  lowered 
into  the  test  bottle,  as  shown  in  the  illus- 
tration. If  the  water  rises  from  0  to  10 
on  the  neck  when  the  upper  point  of  the 
measure  is  submerged  in  the  water,  the 
scale  is  correct.  If  greater  variations  than 
.2  per  cent,  occur,  the  bottle  should  be  re- 
jected. 

The  figure  shows  one  of  these  calibrators 
made  in  two  sections,  so  that  the  accuracy 
of  the  5  per  cent.,  as  well  as  the  10  per 
cent,  mark  on  the  scale  may  be  ascer- 
tained. 

56.  The  standard  measure.  In  the  place 
of  an  iron  nail,  as  originally  proposed,  a 
piece  of  metal  or  glass  rod  may  be  advan-  Trowbidge  Sf- 
tageously  used  as  a  standard  measure.  The  ibrator- 
standardization   of  this  measure  is  most  conveniently 


Tke  Babcock  Test.  51 

done  by  weighing.  Since  the  specific  gravities  of  iron, 
copper,  brass,  and  glass  are  7.2,  8.7,  8.5,  and  about  2.7, 
respectively,  pieces  of  these  materials  replacing  2  cc.  of 
a  liquid,  will  weigh  14.,  17.4,  17.0  and  5.4  grams,  for 
iron,  copper,  brass  and  glass  in  the  order  given. 

A  measure  of  the  right  weight  may  be  suspended  by 
a  very  fine  copper  or  platinum  wire  (melted  into  the 
glass  rod  if  this  material  be  chosen),  and  is  used  di- 
rectly for  calibrating  test  bottles  as  described  above. 
Before  a  measure  so  made  is  used  as  a  standard,  its  ac- 
curacy should  be  determined  by  weighing  the  amount 
of  water  of  a  temperature  of  20°  C.,  which  it  replaces. 
The  specific  gravity  of  glass  especially,  varies  somewhat 
according  to  its  composition,  so  that  a  standardization 
of  a  measure  by  weight  alone  cannot  be  depended  upon 
to  always  give  correct  results. 

In  submerging  the  measure  in  the  test  bottle  to  be 
calibrated,  care  must  be  taken  that  all  air  bubbles  are 
removed  before  the  position  of  the  meniscus  of  the 
water  is  noted ;  if  a  metal  standard  measure  is  used,  it 
must  be  kept  free  from  rust  or  tarnish. 

57.  (C.)  Calibration  with  mercury.  27.10  grams  of 
metallic  mercury  are  weighed  into  the  perfectly  clean  and  dry 
test  bottle.  Since  the  specific  gravity  of  mercury  is  13.55. 
double  this  quantity  will  occupy  a  volume  of  exactly  2  cubic 
centimeters  (48).  The  neck  of  the  test  bottle  is  then  closed 
with  a  small,  smooth  and  soft  cork,  or  a  wad  of  absorbent  cot- 
ton, cut  off  square  at  one  end,  the  stopper  being  pressed  down 
to  the  first  line  of  the  graduation.  The  bottle  is  now  inverted 
so  that  the  mercury  will  run  into  its  neck.  If  the  total  space 
included  between  the  0  and  10  marks  is  just  filled  by  the  two 
cubic  centimeters  of  mercury,  the  graduation  is  correct. 

The  mercury  may  be  conveniently  transferred  from  one  test 
bottle  to  another,  by  means  of  a  thin  rubber  tube  which  is 
slipped  over  the  end  of  the  necks  of  both  bottles,  and  one  weigh 


52  Testing  Milk  and  Its  Products. 

ing  of  mercury  will  thus  suffice  for  a  number  of  calibrations. 
In  transferring  the  mercury,  care  must  be  taken  that  none  of  it 
is  lost,  and  that  small  drops  of  mercury  are  not  left  sticking  to 
the  walls  of  the  bottle  emptied.  A  sharp  tap  on  the  bottle 
with  a  lead  pencil  will  help  to  remove  minute  drops  of  mercury 
from  the  inside.  Unless  the  bottles  to  be  calibrated  are  per- 
fectly clean  and  dry,  it  is  impossible  to  transfer  all  the  mer- 
cury from  one  bottle  to  another. 

After  several  calibrations  have  been  made,  the  mercury  should 
be  weighed  again  in  order  to  make  certain  that  none  has  been 
lost  by  the  various  manipulations.  Scales  similar  to  those  shown 
under  (91)  are  sufficiently  delicate  for  making  these  weighings. 

58.  Test  bottles  may  also  be  calibrated  with  mercury  by  weigh- 
ing the  bottles  filled  with  mercury  to  the  zero  mark,  and  again 
when  filled  to  the  10  mark.     This  is  the  official  method  for  test- 
ing bottles  adopted  by  the  Association   of   Official   Agricultural 
Chemists  (see  306). 

59.  Cleaning  mercury.    Even  with  the  best  of  care,  mercury 
used  for   calibration  of   glassware   will  gradually   become  dirty, 
so  that  it  will  not  flow  freely  over  a  clean  surface  of  glass.     It 
may  be  cleaned  from  mechanical  impurities,  dust,  grease,  water, 
etc.,  by  filtration  through  heavy  filter  paper.     This  is  folded  in 
the  usual  way,  placed  in  an  ordinary  glass  funnel  and  its  point 
perforated  with  a  couple  of  pin  holes.     The  mercury  will   pass 
through    in    fine    streams,    leaving   the    impurities    on    the    filter 
paper.     Mercury  may  be  freed  from  foreign  metals,  zinc,  lead, 
etc.,   sometimes  noticed   as  a  grayish,    thin   film   on   its  surface, 
by  leaving  it  in  contact  with  common  nitric  acid  for  a  number 
of  hours;   the  mercury  is  best  placed  in  a  shallow  porcelain  or 
graniteware   dish   and   the  nitric  acid  poured   over   it,   the   dish 
being  covered  to  keep  out  dust.     The  acid  solution  is  then  care- 
fully poured  off  and  the  mercury  washed  with  water;  the  latter 
is  in  turn  poured  off,  and  the  last  traces  of  water  absorbed  by 
means  of  clean,  heavy  filter  paper. 

The  mercury  to  be  used  for  calibration  of  glassware  should 
be  kept  in  a  strong  bottle,  closed  by  an  ordinary  stopper.  In 
handling  mercury,  care  must  be  taken  not  to  spill  any  portion 
of  it;  finger-rings  should  be  removed  when  calibrations  with  mer- 
cury are  to  be  made. 

Mercury  forms  the  most  satisfactory  and  accurate  material 
for  calibration  of  test  bottles,  on  account  of  its  heavy  weight 


The  Babcock  Test.  53 

and  the  ease  with  which  it  may  be  manipulated.  Equally  correct 
results  may,  however,  with  proper  care  be  obtained  by  using 
water  for  the  calibration. 

60.  Intermediate   divisions.     The  space   between   0 
and  10  on  the  scale  of  the  Babcock  test  bottle  is  divided 
into   50   divisions,   each   five   of   which,   as   previously 
shown,  represent  1  per  cent.    (44).     Since  these  in- 
termediate divisions  are  generally  made  with  a  dividing 
machine,  they  are  as  a  rule  correct,  but  it  may  happen 
that  they  have  been  inaccurately  placed,  although  the 
space  between  0  and  10  is  correct.    The  accuracy  of  the 
intermediate   divisions   can   be   ascertained   by   sliding 
along  the  scale  a  strip  of  paper  upon  which  has  been 
marked  the  space  occupied  by  one  per  cent.,  and  com- 
paring this  space  with  those  of  each  per  cent,  on  the 
scale. 

61.  Calibration    of    skim    milk    test    bottles.      The 
value  of  each  division  on  the  common  double-necked 
skim  milk  bottles  (99)   is  one-twentieth,  or  .05  of  one 
per  cent. ;  there  are  ten  of  these  divisions  in  the  whole 
scale  which,  therefore,  measures  .5  per  cent,  of  fat.    It 
requires  very  careful  work  to  calibrate  this  scale  and  it 
is  best  done  by  weighing  the  amount  of  mercury  which 
will  just  fill  the  space  of  .1  cc.  between  the  first  and  the 
last  divisions  (53)  ;  the  correct  weight  of  this  mercury 
is  1.355  grams. 

62.  Calibration  of  cream  test  bottles.  The  cream  bot- 
tles may  be  calibrated  by  any  of  the  methods  given  for 
milk  bottles.    The  neck  of  a  cream  test  bottle  that  meas- 
ures thirty  per  cent,  fat  will  hold  6  cc.,  and  6  grams  of 
water  or  81.30  grams  of  mercury. 

The  Trowbridge  method  of  calibrating  milk  test  bot- 


54  Testing  Milk  and  Its  Products. 

ties  will  also  be  found  convenient  for  cream  bottles  and 
the  same  standard  measure  used,  the  part  of  the  scale 
from  0  to  10  being  calibrated  first,  then  that  from  10  to 
20,  20  to  30,  30  to  40  per  cent.,  etc.,  in  the.  same  way. 

63.  Pipette  and  acid  cylinder.    The  pipette  and  the 
acid  cylinder  used  in  the  Babcock  test  may  be  calibrated 
by  any  of  the  methods  already  given.     Sufficiently  ac- 
curate results  are  obtained  by  weighing  the  quantity  of 
water  which  each  of  these  pieces  of  apparatus  will  de- 
liver, viz.,  17.5  grams.    The  necessity  of  previous  thor- 
ough cleaning  of  the  glassware  is  evident  from  what  has 
been  said  in  the  preceding.     The  pipette  and  the  acid 
measure  may  be  weighed  empty  and  then  again  when 
filled  to  the  mark  with  pure  water,  or  the  measureful  of 
water  may  be  emptied  into  a  small  weighed  vessel,  and 
this  weighed  a  second  time.     In  either  case  the  weight 
of  the  water  contained  in  the  pipette  or  acid  measure  is 
obtained  by  difference.1 

Calibrations  of  the  acid  cylinder  are  generally  not 
called  for,  except  as  a  laboratory  exercise,  since  small 
variations  in  the  amount  of  acid  measured  out  do  not 
affect  the  accuracy  of  the  test. 

2.— CENTRIFUGAL  MACHINES. 

64.  The  capacity  of  the  testing  machine  to  be  selected 
should  be  governed  by  the  number  of  tests  which  are 
likely  to  be  made  at  one  time.    For  factory  purposes  a 

1One  cubic  centimeter  of  distilled  water  weighs  1  gram,  when 
weighed  In  a  vacuum  at  the  temperature  of  the  maximum  density  of 
water  (4*  C.)  ;  for  the  purpose  of  calibration  of  glassware  used  In  the 
Babcock  test,  sufficiently  accurate  results  are,  however,  obtained  by 
weighing  the  water  in  the  air  and  at  a  low  room  temperature  (60*  P.) 


The  Babcock  Test.  55 

twenty-four  or  a  thirty-two  bottle  tester  is  large  enough, 
and  to  be  preferred  to  a  larger  tester,  even  if  a  large 
number  of  samples  are  to  be  tested  at  a  time.  The 
operator  can  use  his  time  more  economically  in  running 
a  machine  of  this  size  than  one  holding  fifty  or  sixty 
bottles;  the  work  of  filling  or  cleaning  the  bottles  and 
measuring  the  fat  can  be  done  while  the  tester  is  run- 
ning if  a  double  supply  of  bottles  is  at  hand.  Large 
testers  require  more  power  than  smaller  ones,  and  when 
sixty  tests  are  made  at  a  time,  the  fat  column  in  many 
bottles  will  get  cold,  before  the  operator  has  time  to 
read  them,  unless  special  precautions  are  taken  for 
keeping  the  bottles  warm. 

65.  The  tester  should  be  securely  fastened  to  a  solid 
foundation  and  set  so  that  the  revolving  wheel  is  level. 
The  latter  must  be  carefully  balanced  in  order  that  the 
tester  may  be  run  smoothly  at  full  speed.  A  machine 
that  trembles  when  in  motion  is  neither  satisfactory  nor 
safe,  and  the  results  obtained  are  apt  to  be  too  low. 
High-standing  machines  are  more  likely  to  cause  trouble 
in  this  respect  than  low  machines,  and  should  there- 
fore be  subjected  to  a  severe  test  before  they  are  ac- 
cepted. 

If  all  sockets  are  not  filled  with  bottles  when  a  test 
is  to  be  made,  the  bottles  must  be  placed  diametrically 
opposite  one  another  so  that  the  machine  will  be  bal- 
fineed  when  run.  The  bearings  should  be  kept  clean  and 
be  oiled  with  as  much  care  as  the  bearings  of  a  cream 
separator. 

The  cover  of  the  machine  should  always  be  kept 
closed  while  the  bottles  are  whirled,  and  should  not  be 


56  Testing  Milk  and  Its  Products. 

removed  until  the  machine  stops;  it  should  be  tight 
fitting,  since  test  bottles  sometimes  break  while  the  ma- 
chine is  running  at  full  speed,  and  every  possible  pre- 
caution should  be  taken  to  protect  the  operator  from 
any  danger  from  spilled  acid  or  broken  glass. 

66.  Speed  required  for  the  complete  separation  of 
the  fat.  There  is  a  definite  relation  between  the  diame- 
ter of  the  Babcock  testers  and  the  speed  required  for  a 
perfect  separation  of  the  fat.  In  the  preliminary  work 
with  the  Babcock  test  the  inventor  found  that  with  the 
machine  used,  the  wheel  of  which  had  a  diameter  of 
eighteen  inches,  it  was  necessary  to  turn  the  crank  so 
as  to  give  the  test  bottles  seven  or  eight  hundred  revo- 
lutions per  minute,  in  order  to  obtain  a  maximum  sepa- 
ration of  fat  ;  later  work  has  shown  that  this  speed  is 
ample.  Taking  the  higher  figure  as  a  standard,  the  cen- 
trifugal force  to  which  the  contents  of  the  test  bottles 
are  subjected  when  supported  on  an  eighteen-inch  wheel 
and  turned  800  revolutions  per  minute,  can  be  calcu- 
lated as  follows: 

The  centrifugal  force,  F,  acting  on  the  bottles  is  expressed  by 
the  formula 


in  which  w  =  the  weight  of  the  bottle  with  contents,  in  pounds  ; 
v  =  the  velocity,  in  feet  per  second,  and  r  =  the  radius  of  the 
wheel  in  feet  with  the  cups  in  a  horizontal  position. 

When  the  wheel  is  turned  800  times  a  minute,  a  bottle  sup- 
ported on  its  rim  will  travel  2*rX  8-j£  =2  X3.1415  X  -  X^°  =62.83 

M  w  12       600 

feet  per  second.  The  weight  of  a  bottle,  with  milk  and  acid,  is 
about  3  ounces,  or  ^  of  a  pound.  Substituting  these  values 
for  v  and  w,  gives 


The  Babcock  Test.  57 


The  bottles  are,  therefore,  under  the  conditions  given,  sub- 
jected to  a  pressure  of  about  30.65  pounds.  In  order  to  calcu 
late  the  speed  required  for  obtaining  this  force  in  case  of  ma- 
chines of  other  diameters,  the  value  of  v  in  formula  (I)  is 
found  from 


Substituting  the  values  for  F  and  w,  we  have 
- 


In  this  equation  the  values  r  =  5,  6,  7,  8,  9,  10,  11,  12  inches 
are  substituted  in  each  case  (^,  «2,  ^,  .  .  \$),  and  the 
velocity  in  feet  per  second  then  found  at  which  the  bottles  are 
whirled  when  placed  in  wheels  of  diameters  10  to  24  inches,  and 
subjected  in  each  case  to  a  centrifugal  force  of  30.65  Ibs.  As 

the  number  of  revolutions  per  minute  —  -  —  .  v  being  as  before 
the  velocity  in  feet  per  second,  and  r  the  radius  of  the  wheel; 
the  speed  at  which  the  wheel  must  be  turned  is  found  by  sub- 
stituting for  v  the  values  obtained  in  the  preceding  calculations 
in  case  of  wheels  of  different  diameters.  The  results  of  these 
calculations  are  given  in  the  following  table: 

Diameter  Velocity  in  Jeet  Number  of  revolutions 

of  wheel,  D.  per  second,  v.  of  wheel  per  minute. 

10  46.84  1074 

12  51.31  980 

14  55.43  909 

16  59.26  848 

18  62.84  800 

20  66.24  759 

22  69.47  724 

24  72.56  693 

These  figures  show  that  a  tester,  e.  g.,  24  inches  in  diameter, 
will  require  less  than  700  revolutions  per  minuate  for  a  perfect 
separation  of  the  fat  in  Babcock  bottles,  while  a  ten-inch  tester 
must  have  a  speed  of  nearly  1100  revolutions  in  order  to  obtain 
the  same  result. 


58  Testing  MUk  and  Its  Products. 

The  speed  at  which  testers  of  different  diameters  should  be 
run  to  effect  a  complete  separation  has  been  calculated  by  Prof. 
C.  L.  Beach  in  the  following  manner.1  The  same  standard  as 
before  is  taken,  viz.,  800  revolutions  for  an  18-inch  tester  (radius 
9  inches) ;  then  if  x  designate  the  radius  of  the  tester  and  y  the 
speed  required,  we  have 

xy*=9X8002,  or 


/  9  X8002 

fv 

The  figures  obtained  by  the  use  of  this  formula  are  similar 
to  those  given  in  the  preceding  table. 

67.  To  find  the  number  of  turns  of  the  handle  corre- 
sponding to  the  number  of  revolutions  made  by  the 
wheel,  the  handle  is  given  one  full  turn,  and  the  number 
of  times  the  wheel  revolves,  is  noted.  If  the  wheel  has 
a  diameter  of  20  inches  and  revolves  12  times  for  one 
turn  of  the  handle,  the  latter  should  be  turned  ^  =63 
times  a  minute  (see  table),  or  about  once  every  second, 
in  order  to  effect  a  maximum  separation  of  fat.  By 
counting  the  number  of  revolutions,  watch  in  hand, 
and  consulting  the  preceding  table,  the  operator  will 
soon  know  the  speed  which  must  be  maintained  in  case 
of  his  particular  machine.  It  is  vitally  important  that 
the  required  speed  be  always  kept  up ;  if  through  care- 
lessness, worn-out  or  dry  bearings,  low  steam  pressure, 
etc.,  the  speed  is  slackened,  the  results  obtained  will  be 
too  low ;  it  may  be  a  few  tenths,  or  even  more  than  one 
per  cent.  Care  as  to  this  point  is  so  much  the  more 
essential,  as  the  results  obtained  by  too  slow  whirling 
may  seem  to  be  all  right,  a  clear  separation  of  fat  and 

1  Private  romnu—  'cation. 


The  Babcock  Test.  69 

good  duplicates  beiug  often  obtained,  even  when  the 
fat  is  not  completely  separated. 

68.  Ascertaining  the  necessary  speed  of  testers.  In 
buying  a  tester  the  operator  should  first  of  all  satisfy 
himself  at  what  speed  the  machine  must  be  run  to  give 
correct  results;  the  preceding  table  will  serve  as  a  guide 
on  this  point.  He  should  measure  out  a  dozen  tests  of 
the  same  sample  of  milk,  and  whirl  half  the  number  at 
the  speed  required  for  machines  of  the  diameter  of  his 
tester.  Whirl  the  other  half  at  a  somewhat  higher 
speed.  If  the  averages  of  the  two  sets  of  determinations 
are  the  same,  within  the  probable  error  of  the  test  (say, 
less  than  one-tenth  of  one  per  cent),  the  first  whirling 
was  sufficient,  as  it  is  believed  will  generally  be  the  case. 
If  the  second  set  of  determinations  come  higher  than  the 
first  set,  the  first  whirling  was  too  slow,  and  a  new  series 
of  tests  of  the  same  sample  of  milk  should  be  made  to 
ascertain  that  the  speed  in  the  second  set  of  determina- 
tions was  sufficient. 

This  method  will  test  not  only  the  speed  required 
with  the  particular  machine  at  hand,  but  will  also  serve 
to  indicate  the  correctness  of  the  calibration  of  the  bot- 
tles. A  large  number  of  tests  of  the  same  sample  of 
milk  made  as  directed  (pouring  the  milk  once  or  twice 
previously  to  taking  out  a  pipetteful  for  each  test) 
should  not  vary  more  than  two-tenths  of  one  per  cent, 
at  the  outside,  and  in  the  hands  of  a  skilled  operator 
will  generally  come  within  one-tenth  of  one  per  cent. 
If  greater  discrepancies  occur,  the  test  bottles  giving 
too  high  or  too  low  results  should  be  further  examined, 
and  calibrated  according  to  the  directions  already  given 
(53  et  sea.). 


60  Testing  MUk  and  Its  Products. 

69.  Hand  testers.  When  only  a  few  tests  are  made 
at  a  time,  and  at  irregular  intervals,  as  in  case  of  dairy- 
men who  test  single  cows  in  their 
herds,  a  small  hand  tester  answers 
every  purpose.  These  may  be  had  in 
sizes  from  two  to  twelve  bottles.  In 
selecting  a  particular  make  of  tester 
the  dairyman  has  the  choice  of  a  large 
Babcock  band  testers,  number  of  different  machines.  Most  of 
the  first  machines  placed  on  the  market  for  this  purpose 
were  so  cheaply  and 
poorly  constructed  as 
to  prove  very  unsat- 
isfactory after  hav- 
ing been  in  use  for  a 
time.  The  competi- 
tion between  manu- 
facturers of  dairy 
supplies  and  the 
demand  of  dairymen 

for  something  cheap,     FIG.  21.     Type  of  Babcock  hand  testers. 

fully  account  for  this  condition  of  affairs.  This  ap- 
plies especially  to  the  early  machines  made  with  belts 
or  friction  application  of  power.  Hand  testers  made 
with  cog-geared  wheels  can  be  depended  on  to  give  the 
necessary  speed  when  run  according  to  the  manufactur- 
ers' directions;  the  earlier  machines  of  this  kind  were 
very  noisy,  but  at  the  present  time  the  best  machines 
on  the  market  are  of  this  type.  These  are  provided 
with  spiral  cog-gearing  and  ball  bearings,  are  strongly 
made  and  will  run  smoothly  and  with  little  noise  (figs 


The  Babcock  Test. 


61 


20  and  21) ;  in  cog-geared  machines  the  bottles  are  al- 
ways whirled  at  the  speed  which  the  number  of  turns 
made  by  the  crank  would  indicate. 

70.  Power  testers.   For  factory  purposes,  steam  tur- 
bine machines  (figs.  22-24)   are  most  satisfactory  when 
well  made  and  well  cared  for.     They  should  be  pro- 
vided    with    a    speed    indi- 
cator and  steam  gauge,  both 

for  the  purpose  of  knowing 
that  sufficient  speed  is  at- 
tained, and  to  prevent  what 
may  be  serious  accidents 
from  a  general  smash-up,  if 
the  turbine  "runs  wild"  by 
turning  on  too  much  steam. 
The  revolving  wheel  of  the 
tester  should  be  made  of 
wrought  or  malleable  iron,  or 
of  wire,  so  that  it  will  not  be  broken  by  the  centrifugal 
force  and  cause  accidents.  The  swinging  pockets 
which  hold  the  test  bottles  in  most  machines  should 
be  so  made  that  the  bottles  will  not  strike  the 
center  of  the  revolving  frame  when  in  a  horizontal  posi- 
tion. Tests  have  often  been  lost  by  the  end  of  the  neck 
catching  at  the  center,  the  bottles  thus  failing  to  take 
an  upright  position  when  the  whirling  stops. 

71.  The  exhaust  steam  pipe  of  turbine  testers  should 
not  have  too  many  turns  or  be  much  reduced  in  size 
from  that  of  the  opening  in  the  tester.    A  free  escape 
of  the  exhaust  steam  is  necessary  to  prevent  the  steam 
from  collecting  in  the  test  bottle  chamber  and  overheat- 
ing the  test  bottles  when  whirled  (41). 


FIG.  22.     Type  of  Babcock  steam 
turbine  testers. 


Testituj  Milk  and  Its  I 'rod  net  a. 


The  covers  of  some  testers  have  an  opening  provide;! 
with  a  sliding  damper  or  some  arrangement  by  which 
it  can  be  closed  when  desired.  If  whole  milk  or  cream 
is  being  tested,  this  hole  should  be  open  so  that  a  draft 
of  air  may  enter  the  chamber  during  the  whirling  ana 
force  the  steam 
into  the  exhaust 
pipe.  If  skim  milk 
is  being  tested,, 
the  opening  in  the 
cover  should  be 
closed.  This  shuts 
off  the  draft  of 
air,  and  the  ex- 
haust steam  heats 
the  test  bottles 
during  whirling 
to  200  degrees  F. 
in  some  cases. 
This  high  tern-. 


perature    aids 


FIG.  23.      Type 


FIG.    24.     Type  of  Babcock  turbine  testers 
(for  testing  cream  in  9-in.  cream  bottles) 


turbine  testers. 

separating     the     fat 
in    skim     milk     and 
gives     fairly     cor- 
rect tests   of  sam- 
ples  containing   less 
than    one-tenth    per 
cent  fat   (98).  Some 
turbine  testers  are 
provided          with 
holes  in  the  covers 
and   a  thermome- 
ter   is    placed     in 
the  cover. 


The  Babcock  Test. 


63 


Babcock  testers  run  by  electricity  have  lately  been 
put  on  the  market  by  several  manufacturers  (fig. 
25).  Where  no 
steam,  but  elec- 
trical current  is 
available,  these 
machines  may 
be  installed  to 
great  advantage, 
as  they  are  con- 
venient to  use 
and  may  be  de- 
pended on  to 
run  at  the  re- 
quired speed. 
S-ome  provision 
for  getting  hot 
water  must  be  at  hand  in  using  electrical  Babcock 
testers.1 

3.— SULPURIC  ACID. 

72.  The  sulfuric  acid  to  be  used  in  the  Babcock  test 
should  have  a  specific  gravity  of  1.82-1.83.2  Commer- 
cial sulfuric  acid  (sometimes  called  oil  of  vitriol)  is 
always  used;  it  can  be  bought  for  about  2  cents  a 
pound  in  carboy  lots  and  25  cents  or  less  a  quart  at  re- 
tail. One  quart  of  acid  is  sufficient  for  fifty  tests.  The 
acid  should  be  kept  in  glass  bottles  or  jugs,  prefer- 
ably glass  or  rubber  stoppered  ones,  since  a  cork  stop- 

1  The  method  of  installation  of  a  40-bottle  electrical  Babcock  tester  is 
described  in  detail  in  Rept.  Dept.  of  Health,  City  of  Chicago,  1906,  p.  18. 

ZA  specific  gravity  of  1.82  means  that  a  given  volume  of  the  acid 
weighs  1.82  times  as  much  as  the  same  volume  of  water  at  the  same 
temperature  (see  also  under  Lactometer,  109). 


FIG.  25.     Type  of  Babcock  electrical  testers. 


64  Testing  Milk  and  Its  Products. 

per  is  soon  dissolved  by  the  acid  and  rendered  useless. 
If  the  bottle  is  left  uncorked,  the  acid  will  absorb 
moisture  from  the  air  and  after  a  time  will  become  too 
weak  for  use  in  this  test. 

Lead  is  the  only  common  metal  which  is  not  dissolved 
by  strong  sulfuric  acid ;  where  considerable  milk  testing 
is  done,  it  is  therefore  desirable  to  provide  a  small 
table  or  tray  covered  with  sheet  lead  on  which  the  acid 
may  be  handled.  The  acid  dissolves  iron,  tin,  wood 
and  cloth,  and  burns  the  skin.  If  acid  is  accidentally 
spilled,  plenty  of  water  should  be  used  at  once  to  wash 
it  off.  Ashes,  potash,  soda,  and  ammonia  neutralize 
the  action  of  the  acid,  and  a  weak  solution  of  any  one 
of  these  alkalies  should  be  used  after  the  acid  has  been 
washed  off  with  water.  The  red  color  caused  by  the 
action  of  weak  acid  on  clothing  can  be  removed  by 
wetting  the  spot  with  dilute  ammonia;  this  must,  how- 
ever, be  applied  while  the  stain  is  fresh,  and  is  in  its 
turn  washed  off  with  water. 

73-  Testing  the  strength  of  acid.  The  strength  of 
the  acid  can  be  easily  tested  by  the  use  of  a  balance  like 
that  shown  in  fig.  34  (91).  A  dry  test  bottle  is  weighed, 
and  then  filled  with  acid  exactly  to  the  zero  mark,  or 
to  any  other  particular  line  of  the  scale.  It  is  then 
again  weighed  accurately;  the  difference  between  the 
two  weights  will  give  the  weight  .of  the  acid  in  the  bot- 
tle. The  bottle  is  then  emptied  and  thoroughly  rinsed 
with  water  (until  the  water  has  no  longer  an  acid 
taste) ;  it  is  then  filled  with  pure  water  to  the  same  line 
as  before  and  weighed;  the  difference  between  this 
weight  and  that  of  the  empty  bottle  gives  the  weight 


The  Babcock  Test.  (55 

of  the  same  volume  of  water  as  that  of  the  acid 
weighed.  The  specific  gravity  of  the  acid  is  obtained 
by  dividing  the  weight  of  the  acid  by  the  weight  of  the 
water.  If  the  quotient  comes  between  1.82  and  1.83 
the  acid  is  of  correct  strength.  The  outside  of  the 
test  bottle  should  always  be  wiped  dry  before  the 
liquids  are  weighed.  Unless  great  care  is  taken  in 
measuring  the  acid  and  the  water,  and  in  weighing 
both  these  and  the  test  bottle,  the  results  obtained  will 
not  be  trustworthy. 

74.  Acid  that  is  a  little  too  strong  can  be  used  by 
taking  less  than  the  required  amount  for  each  test,  e.  g., 
about  15  cc.  Operators  are  warned  against  reducing 
the  strength  of  the  acid  by  adding  water  to  it,  as  acci- 
dents may  easily  occur  when  this  is  done.  A  too  strong 
acid  can.  if  desired,  be  weakened  by  simply  leaving  the 
bottle  uncorked  for  a  time,  or  by  pouring  the  acid  into 
a  bottle  containing  a  small  quantity  of  water.  In  the 
latter  case  the  first  portions  of  acid  should  be  added 
carefully,  a  little  at  a  time,  shaking  the  bottle  after 
each  addition,  so  as  not  to  cause  it  to  break  on  account 
of  the  heat  evolved  in  mixing  the  acid  and  the  water. 
Never  dilute  sulfuric  acid  by  pouring  water  into  it. 

A  helpful  suggestion  for  using  acid  that  is  too  strong 
or  would  give  a  charred  fat  on  account  of  high  tem- 
perature of  acid  or  milk,  or  both,  has  been  made  by  M. 
L.  Holm,  Assistant  Chemist  Chicago  Dept.  of  Health, 
viz.,  to  add  2  cc.  of  80  per  cent,  glycerin  (80  parts  of 
commercial  glycerin  and  20  parts  of  water,  by  volume) 
to  the  milk  sample,  prior  to  adding  the  acid.1  The  gly- 

1  American  Food  Journal,  1907,  No.  7,  p.  28  ;  Hoard's  Dairyman,  Nov. 
S.  1907. 


66  Testing  Milk  and  Its  Products. 

cerin  protects  the  milk  to  some  extent  from  the  acid  be- 
fore the  two  are  mixed,  and  a  clear  fat  may  thus  often 
be  secured  under  otherwise  unfavorable  conditions.  The 
results  appear  not  to  be  influenced  by  the  addition  of 
the  glycerin. 

75.  If  the  acid  is  a  little  too  weak,  correct  results 
may  be  obtained  by  using  more  than  the  specified  quan- 
tity, say  20  cc.    If  a  good  test  is  not  obtained  with  this 
quantity  of  acid,  a  new  lot  must  be  secured,  as  its  spe- 
cific gravity  in  such  a  case  is  below  1.82.    The  observing 
operator  will  soon  be  able  to  judge  of  the  strength  of 
the  acid  by  its  action  on  milk  in  mixing  the  two  liquids 
in  the  Babeock  test  bottles;   it  is  indeed   remarkable 
what  slight  differences  in  the  specific  gravity  of  the 
acid  will  make  themselves  apparent  in  working  the  test, 
as  regards  the  rapidity  with  which  both  the  curdled 
milk  is  dissolved  and  the  mixture  of  acid  and  milk  turns 
black. 

76.  Strength  of  sulfuric  acid.    The  relation  between 
the  strength  of  sulfuric  acid  and  its  specific  gravity 
will  be  seen  from  the  following  table: 

Specific  Gravity  of  Sulfuric  Acid  of  Different  Strength. 


Specific  Gravity  Rulfurlo  Acid 

flS'C.,  water  t'C.).  (H.80.) 

1.841 97  percent 

1.840 _  96 

1.839 95 

1.837 94 

1.834 ,_   _  _  93 

1,830 92 

1.825 .  _  91 

1.820 90 

1.815 ...       "89 

1.808___  88 


The  Bdbcock  Test.  67 

It  will  be  noticed  that  the  sulfuric  acid  to  be  used  in 
the  Babcock  test  should  contain  90  to  92  per  cent,  of 
acid  (H2SOJ  ;  slightly  weaker  or  stronger  acid  than 
this  may,  as  previously  stated,  be  used  by  varying  the 
quantity  of  acid  taken  for  each  test  according  to  the 
strength  of  the  acid,  but  successful  tests  cannot,  as  a 
rule  be  made  with  acid  weaker  than  89  per  cent,  or 
stronger  than  95  per  cent. 

77.  The  Swedish  acid  tester  is  a  small  hydrometer,  intended 
to  show  whether  the  acid  used  in  the  Babcock  test  is  of  the  cor- 
rect strength.     An  examination  of   these  testers  will  show  that 
they  are  practically  useless  for  the  purpose  intended,  from  the 
fact  that   they   are   not    sufficiently   sensitive;    while   the   testers 
examined  were  found  to  sink  to  the  line  marked  Correct  on  the 
scale,  when   lowered   into   sulfuric  acid  of  a  specific   gravity  of 
1.83,  they  would  sink  to  a  point  much  nearer  the  same  mark, 
than  to  the  lines  marked   Too  strong  or  Too  weak,  respectively, 
when  lowered  into  either  too  strong  or  too  weak  acid 

78.  The  color  of  the  fat  column  an  index   to  the 
strength  of  the  acid  used.     The  strength  of  the  acid 
is  indicated  to  a  certain  extent  by  the  color  of  the  fat 
which  separates  in  the  neck  of  the  test  bottle  when  milk 
is  tested.    If  the  directions  given  for  making  the  tests 
are  carefully  followed,  the  fat  separated  out  will  be  of 
a  golden  yellow  color.     If  the  fat  is  light  colored  or 
whitish,  it  generally  indicates  that  the  acid  is  too  weak 
and  a  dark  colored  fat,  with  a  layer  of  black  material 
beneath  it,  shows  that  the  acid  is  too  strong,  provided 
the  temperature  of  both  milk  and  acid  is  about  70°. 
[For  influence  of  temperature,   see   next    paragraph.] 
The  acid  used  in  the  test  is  not  of  sufficient  strength 
to  appreciably  attack  the  fat  at  ordinary  temperatures 
of  testing,  but  a  variation  in  the  strength  of  the  acid 


68  Testing  Milk  and  Its  Products. 

or  in  the  temperature  of  the  milk  influences  the   in 
tensity  of  the  action  of  the  acid  on  the  fat,  as  indicated 
by  the  color  of  the  fat  obtained. 

79.  Influence  of  temperature  on  the  separa- 
tion of  fat.  The  intensity  of  the  action  of  the  sul- 
furic  acid  on  the  milk  is  influenced  by  the  temperature 
of  either  liquid ;  the  higher  the  temperature,  the  more 
intense  will  be  the  action  of  the  acid  on  the  solids  of 
the  milk. 

The  following  experiment  shows  the  relation  between 
the  strength  of  the  acid,  the  temperature  of  the  milk 
and  the  color  of  the  fat: 

First: — From  a  sample  of  milk  measure  the  usual  -quantity 
for  testing  into  each  of  three  bottles,  A,  B  and  C.  Place  A  in 
iced  water,  and  C  in  warm  water,  leaving  bottle  B  at  ordi- 
nary temperature.  After  the  bottles  havtj  been  left  for  ten  min- 
utes under  these  conditions,  add  the  normal  quantity  of  acid 
to  each  and  proceed  with  the  test  in  the  ordinary  manner. 

Second: — Measure  some  of  the  same  milk  into  three  other 
bottles,  D,  E  and  F.  Into  test  bottle  D  pour  the  usual  amount 
of  rather  weak  acid;  add  the  same  amount  of  acid  of  normal 
strength  (1.82-1.83)  to  bottle  E,*  and  add  17.5  cc.  of  a  still 
stronger  acid  (concentrated  sulfuric  acid,  sp.  gr.  1.84),  in  test 
bottle  F;  complete  the  tests  in  the  usual  way. 

On  the  completion  of  the  preceding  six  tests  the  operator  will 
notice  that  the  fat  in  the  necks  of  test  bottles  A  (cold  milk) 
and  D  (weak  acid)  is  much  lighter  colored  than  that  in  C  (warm 
milk)  and  F  (strong  acid),  and  that  the  color  of  the  fat  in  B 
(normal  temperature)  and  E  (normal  acid)  is  somewhere  be- 
tween that  of  these  two  series. 

It  may  be  noticed  that  acid  from  the  same  carboy  will 
act  differently  on  milk  in  summer  than  in  winter  time, 
if  the  acid  and  the  milk  are  not  brought  to  a  tempera- 
ture of  about  70°  before  testing  during  both  seasons. 
The  temperature  of  the  liquids  may  be  as  low  as  40°  P. 
in  winter  and  as  high  as  80°  F.  in  summer.  This  dif- 


The  Babcock  Test.  69 

ference  of  forty  degrees  will  often  have  considerable 
influence  on  the  clearness  of  the  fat  separated,  show- 
ing white  curdy  substances  and  a  light  colored  fat  in 
winter,  or  black  flocculent  specks,  with  a  dark  colored 
column  of  fat  in  summer.  Both  these  defects  can  be 
avoided,  when  the  acid  is  of  the  proper  strength,  by 
bringing  the  temperature  of  the  milk  and  the  acid  to 
about  70°  F.  before  the  milk  is  tested. 

The  operator  should  be  particularly  cautious  against 
over-heating  either  milk  or  acid,  since  the  heat  intensi- 
fies the  action  of  the  acid  and  this  may  become  so  vio- 
lent as  to  force  the  hot  liquid  out  of  the  neck  of  the 
test  bottle  when  the  acid  is  added  to  the  milk,  thus 
spoiling  the  test  and  possibly  causing  an  accident. 

4. — WATER  TO  BE  USED  IN  THE  BABCOCK  TEST. 

80.  Pure  rain  water,  condensed  steam,  or  soft  water 
should  be  used  for  the  purpose  of  .bringing  the  fat  into 
the  neck  of  the  test  bottles.  The  surface  of  the  fat  col- 
umn will  then  usually  be  clear  and  distinct.  The  foam  or 
bubbles  that  sometimes  obscure  the  upper  line  (menis- 
cus) of  the  fat,  making  indistinct  the  point  from  which 
to  measure  it,  is  generally  caused  by  the  action  of  the 
acid  on  the  carbonates  in  hard  water.  The  carbonic 
acid  gas  liberated  from  such  water  by  the  sulfuric  acid 
is  held  more  or  less  by  the  viscid  fat  and  produces  a 
layer  of  foam  on  its  surface.  If  clean  soft  water  cannot 
be  obtained  for  this  purpose,  hard  water  may  be  used,  by 
adding  a  few  drops  of  sulfuric  acid  to  the  water  before 
it  is  heated,  thus  causing  the  carbonic  acid  to  be  ex- 


70  Testing  Milk  and  Its  Products. 

pelled.  By  simply  boiling,  many  hard  waters  will  be 
rendered  soft  and  adapted  to  use  in  the  Babcock  test, 
as  most  of  the  carbonates  which  cause  this  foaming  are 
thereby  precipitated. 

If  the  test  has  been  completed,  and  a  layer  of  foam 
appears  over  the  fat,  it  may  be  destroyed  by  adding  a 
drop  or  two  of  alcohol.  If  this  is  done,  the  fat  column 
should  be  read  at  once  after  the  alcohol  is  added,  as 
the  latter  will  soon  unite  with  the  fat  and  increase 
its  volume.  (See  also  96  on  the  use  of  glymol  in  cream 
testing.) 

81.  Reservoir  for  water.  When  only  a  few  tests  are 
made  at  one  time,  hot  water  can  be  added  with  the  17.6 
cc.  pipette.  If  many  tests  are  made,  the  water  may  be 
conveniently  and  quickly  filled  into  the  test  bottles  by 
drawing  it  from  a  small  copper  reservoir  or  tin  pail 
suspended  over  the  testing  machine.1  The  flow  of  water 
through  a  rubber  tube  connected  with  the  reservoir,  is 
regulated  by  means  of  a  pinch  cock.  The  water  must 
be  hot  when  added  to  the  test  bottles  so  as  to  keep  the 
fat  in  a  melted  condition  until  the  readings  are  taken. 
Most  turbine  testers  are  now  made  with  a  very  conven- 
ient water  reservoir  attached  to  the  tester  (figs.  22-24). 

The  use  of  zinc  or  steel  oilers,  or  perfection  oil  cans 
has  been  suggested  as  a  convenient  method  of  adding 
hot  water  to  the  test  bottles,  but  most  operators  prefer 
to  add  water  to  the  bottles  by  means  of  a  piece  of  rub- 
ber tubing  connected  with  a  reservoir,  as  shown  in  the 
illustrations  just  referred  to. 

1  Ordinary  tinware  will  soon  rust  with  water  standing  in  it,  and  cop- 
per reservoirs  are  therefore  more  economical. 


The  Babcock  Test.  71 

5.— MODIFICATIONS  OP  THE  BABCOCK  TEST. 

83.  •   Bartlett's  modification.        Bartlett1  proposed  a  modi- 
fication of  the  method  of  procedure  in  the  Babcock  test,  which 
aims  to  simplify   the  manipulations.     20  cc.  of  acid  are  added, 
instead    of    17.5    cc.,    and    the   bottles    filled    with    the    milk-acid 
mixture  are  left  standing  for  not  less  than  five  minutes  and  then 
filled   with  hot    water  to  within   the  scale;    the  bottles  are   then 
whirled  for  five  minutes  at  the  regular  rate  (52). 

83a.  Siegf  eld's  modification.  The  German  dairy  chemist 
Siegfeld  in  1899  proposed  a  modification  of  the  Babcock  test,2 
using  2  cc.  of  amyl  alcohol  with  the  sulfuric  acid, 
and  filling  up  with  dilute  sulfuric  acid  (1:1,  sp.  gr.,  1.5) 
in  one  filling,  in  place  of  water  after  the  whirling. 
A  dear  separation  of  the  fat  is  facilitated  by  both  thest 
changes,  but  when  properly  conducted,  there  is  no  difficulty 
whatever  in  obtaining  a  clear  fat  column  in  the  Babcock  test 
as  described  in  this  book,  and  the  modification  has  not  there- 
fore been  generally  introduced  in  American  factories.  It 
has,  however,  been  adopted  in  many  German  creameries 
where  the  Babcock  test  is  used. 

84.  Bausch and  Lomb  centrifuge.     Fig.  29    shows  a  fornj 
of   hand   centrifuge    which    may   be   used    to   advantage   by 
physicians  or  in  pathological  laboratories  for  the  determina- 
tion of  fat  in  milk.     The  centrifuge  is  especially  designed  for 
examination  of  urine,  sputum,  blood,  etc.,  but  has  been  adapt- 
ed to  milk  analysis  by  the  Leffmann  &  Beam  test,  a  special 
form  of  bottle  (fig.  30)  having  been  constructed  for  this  pur- 
nose.     The  machine  gives  satisfactory  results  by  the  Babcock 
test  as  well,  provided  the  acid  used  is  1.83-1.84,  or  if  the 
bottles   containing  the   acid-milk  mixture   be   placed   in   hot 
water  for  five  or  ten  minutes  prior  to  the  whirling.     As  the 

'Maine  experiment  station,  bull.  31    (B.  s.) 
*Mollccrei  Ztg.,  1899,  p.  51. 


72  Testing  Milk  and  Its  Products. 

bottles  are  calibrated  for  only  5  cc.  of  milk  and  the  neck  of 
the  bottles,  with  scale,  is  correspondingly  fine,  testing  milk 
with  this  machine  requires  some  nicety  of  manipulation  not 
called  for  in  case  of  regular  Babcok  testers  constructed  for 
the  use  of  factory  operators  and  dairymen. 


FIG.  30. 
Test      bottle 
and     pipette 
for    physician's 
centrifuge. 


Fto.  29.  Physician's  centri 
fuge  that  may  be  used  for  milk 
testing. 


840.  Whitman  milk  bottle.  Dr.  Boss  C.  Whitman  has  de- 
vised another  milk  test  bottle  for  the  special  use  of  physicians 
in  testing  human  milk  and  small  amounts  of  cow's  milk  by  the 
Babcock  test.1  The  bottle,  which  can  be  placed  in  an  ordinary 
urine  centrifuge,  consists  of  two  parts,  a  small  tube  for  hold- 
ing the  milk,  acid  and  water,  and  a  detachable  graduated  fine 
t  ube,  into  which  the  fat  column  is  brought  after  the  final- 
filling  and  whirling.  5  cc.  of  milk  are  used  in  this  test. 


1  Jour.  Amer.   Med.  Asso.,   47    (1906),   p.  204.     See  also  Doran,  Jr. 
Ind.  and  Eng.  Chemistry,  1912,  p.  841. 


The  Babcock  Test.  73 


Questions. 

1.  Give  a  brief  description  of  the  Babcock  test. 

2.  State  precautions  to  be  observed  in  each  of  the  following 
operations:     (a)   Measuring  the  milk,   (b)   adding  the  acid,   (c) 
whirling  the  bottles,  (d)  adding  the  water,  (e)  measuring  the  fat. 
[f  the  fat  separates  clear,  but  the  results  are  evidently  too  low, 
what  is  the  probable  cause,  and  how  can  the  correct  test  be  estab- 
lished! 

3.  To   what  extent  does   the    temperature   of   the   fat,    when 
read,  influence  the  result? 

4.  Explain  the  graduations  of  the  milk  teat  bottle. 

5.  What  is  the  capacity  of  the  neck  of  a  milk  test  bottle  be- 
tween the  0  and  10  marks,  expressed  in  cc.,  and  in  grams  t 

6.  If  the  graduations  of  a  test  bottle  measure  2.3  cc.  from 
0  to  10%,  what  would  be  the  correct  test  of  a  sample  which  reads 
3.4%   fat  in  this  bottle? 

7.  Describe  three  different  methods  of  calibrating  milk   test 
bottles. 

8.  Describe    the    proper    construction    of    the    milk-measuring 
pipette;   what   weight  of  milk  does  it  deliver? 

9.  What  is  a  Swedish  acid  bottle? 

10.  What  speed  is  required  for  testers  having  a  diameter  of 
8,  15,  and  20  inches? 

11.  Write  an  order  for  one  gallon  of  sulfuric  acid  to  be  used 
in  testing  milk. 

12.  How  can  the  strength  of  the  acid  be  tested  at  the  farm  or 
in  a  factory? 

13.  State   precautions  to   be   taken   in   using  an   acid   that   is 
(a)   too  strong,  (b)   too  weak. 

14.  What  does  the  color  of  the  fat  indicate  in  regard  to  the 
strength  of  the  acid  or  the  temperature  of  either  acid  or  milk? 


74 


Testing  Milk  and  Its  Products. 


15.  What  is  the  cause  of  foam  above  the  fat  column,  and  how 
may   it  be  prevented  f 

16.  What  causes  white  curd  or  black  specks  in  the  fatf 

17.  Describe  a  few  modifications  of  the  Babcock  test. 


FIG.  30a.     Scales  used  for  weighing  cream  in  the  Babcock  test 


CHAPTER  IV. 
CREAM   TESTING. 

85.  Cream  may  be  tested  by  the  Babcock  test  in  the 
same  manner  as  milk,  and  the  results  obtained  are  ac- 
curate when  the  necessary  care  has  been  taken  in  sam- 
pling the  cream  and  measuring  the  fat.  The  composi- 
tion of  cream  varies  greatly  according  to  the  process  of 
creaming,  the  temperature  of  the  milk  during  the  cream- 
ing, the  quality  and  the  composition  of  the  milk,  etc. 
The  cream  met  with  in  separator  creameries  will  con- 
tain from  25  to  40  per  cent,  of  fat,  or  on  the  average 
about  35  per  cent.  Cream  from  hand  separators  may 
be  as  rich  as  this,  but  it  often  contains  only  20  per  cent. 


Fro.  81.     Students  testing  dairy  products. 


76  Testing  Milk  and  Its  Products. 

of  fat  as  delivered  to  creameries.  An  average  grade  of 
market  cream  as  retailed  contains  about  25  per  cent,  of 
fat.  If  18  grams  of  25  per  cent,  cream  are  measured 
into  an  ordinary  Babcock  test  bottle,  there  will  be 
18  X  .25=4.5  grams  of  pure  butter  fat  in  the  bottle, 
or,  (since  the  specific  gravity  of  butter  fat  is  about  .9) 
-U.=  5  cc.  It  is  shown  that  the  space  from  0  to  10 
in  the  neck  of  these  bottles  holds  exactly  2  cc.  (44). 
The  neck  of  the  milk  test  bottle  is  not  large  enough  to 
show  the  per  cent,  of  fat  in  a  sample  of  cream  if  18 
grams  are  taken  for  testing,  and  it  is  therefore  neces- 
sary to  adopt  special  measures  when  cream  is. to  be 
tested. 

*6.  Errors  of  measuring  cream.  Several  factors 
tend  to  render  inaccurate  the  measuring  of  cream  for 
the  Babcock  test,  and  correct  results  can  therefore  only 
be  obtained  by  weighing  the  cream.  If  a  17.6  cc.  pi- 
pette is  used  in  testing  the  cream,  it  will  not  deliver 
18  grams  of  cream,  as  it  will  of  milk,  for  the  following 
reasons : 

1.  The  specific  gravity  of  cream  is  lower  than  that  of 
milk;  if  a  certain  quantity  of  milk  weighs  1030  Ibs.,  the 
same  quantity  of  cream  will  weigh  from  1020  Ibs.  to 
1000  Ibs.  or  less,  the  weight  being  determined  by  the 
richness  of  the  cream ;  the  more  fat  the  cream  contains, 
the  less  a  certain  quantity  of  it,  e.  g.,  a  gallon,  will 
weigh.1 

2.  Cream  is  thicker  (more  viscous)  than  milk  at  the 
same  temperature,  and  more  of  it  will  adhere  to  the 
sides  of  the  measuring  pipette  than  in  the  case  of  milk. 

1  For  specific  gravity  of  cream  of  different  richness,  see  table  on  p.  77 


Cream  Testing.  77 

This  is  of  special  importance  in  testing  very  rich  or 
sour  cream. 

3.  In  case  of  separator  cream,  more  or  less  air  will 
become  incorporated  with  the  cream  during  the  process 
of  separation.  In  the  ripening  of  cream,  the  fermenta- 
tion gases  developed  are  held  in  the  cream  in  the  same 
way  as  bread  dough  holds  the  gases  generated  by  yeast. 
In  either  case  the  weight  of  a  certain  measure  of  cream 
is  diminished. 

87.  As  an  illustration  of  the  effect  of  the  preceding 
factors  on  the  amount  of  cream  measured  out  by  a  Bab- 
cock  17.6  cc.  pipette,  the  following  weighings  of  sepa- 
rator cream  are  given  (column  &.)  Thy  cream  was  in 
all  cases  fresh  from  the  separator;  it  was  weighed  as 
delivered  by  the  pipette  into  a  cream  test  bottle  (89), 
and  the  test  proceeded  with  at  once ;  the  specific  gravity 
of  the  cream  was  determined  by  means  of  a  picnometer 
(248).  The  data  given  are  in  all  cases  averages  of  sev- 
eral determinations ;  the  samples  of  cream  have  been 
grouped  according  to  their  average  fat  contents.1 


Per  cent 
of  fat. 
in  cream. 

Specific  y  rarity  (17.5°  C.) 
(a) 

Weight  of  cream  deliv- 
ered, grams. 
(V 

10 

1.023 

17.9 

15 

1.012 

17.7 

20 

1.008 

17.3 

25 

1.002 

17.2 

30 

.996 

17.0 

35 

.980 

16.4 

40 

.966 

16.3 

45 

.950 

16.2 

50 

.947 

15.8 

1  For  Influence  of  condition  of  cream  on  the  amount  measured  out 
with  a  17.6  cc.  pipette,  see  also  Bartlett,  Maine  exp.  sta.,  bull.  31  (S. 
S.)  ;  Jones,  Vt.  exp.  sin.,  report' 1C,  101-6,  and  Donn,  (iiidplt  (Onl.)  ngr 
college,  report  1906,  p.  125. 


78  Testing  Milk  and  Its  Products. 

The  figures  in  the  table  show  plainly  the  variations 
in  the  specific  gravity  of  cream  of  different  richness 
and  the  error  of  making  tests  of  cream  by  measuring  it 
with  a  17.6  cc.  pipette,  especially  if  the  pipette  is  not 
rinsed  and  the  washings  added  to  the  test  bottle.  If  the 
cream  to  be  sampled  is  fresh  separator  cream  testing 
over  30  per  cent.,  less  than  17.0  grams  of  cream  will  be 
delivered  into  the  test  bottle,  and  the  results  of  the 
reading  will  be  at  least  one-eighteenth  too  low  (since 
the  bottles  are  graduated  for  18  grams),  or  about  1.6 
per  cent,  too  low  in  the  case  of  a  30  per  cent,  cream.  If 
the  cream  is  sour,  the  error  will  of  course  be  still  greater. 

It  should  be  remembered  that  the  specific  gravities 
of  the  cream  given  in  the  table  refer  to  fresh  separator 
cream  only.  Considerable  air  is  incorporated  during 
the  separation,  and  cream  of  this  kind  is  therefore  lighter 
than  gravity  cream  of  corresponding  fat  contents. 

Babcock  has  calculated  the  specific  gravity  of  cream 
containing  different  percentages  of  butter  fat,  and  the 
weight  of  one  gallon  of  each;  see  table  XVI  in  the 
Appendix.2 

88.  Weighing  cream  for  testing.  For  the  reasons 
stated  in  the  preceding,  accurate  tests  of  cream  can 
only  be  made  by  weighing  the  cream  into  the  Babcock 
test  bottles.1 

The  simplest  method  is  to  weigh  9  or  18  grams  of  the 
samples  on  a  small  cream- weighing  scale  (see  p.  81)  into 
one  of  the  special  forms  of  cream-test  bottles. 

'This  Is  recognized  by  a  law  passed  by  the  Wisconsin  legislature  In 
1903,  and  by  similar  laws  in  other  .states  which  require  cream 
to  be  weighed  for  testing  where  it  is  sold  on  the  basis  of  its 
fat  content.  (Chapter  43,  Wisconsin  laws  of  1903,  an  act  to 
prescribe  the  standard  measures  for  the  use  of  the  Babcock  test  In  de- 
termining theper  cent,  of  butter  fat  In  milk  or  cream,  i 

'Hoard's  Dairyman,  Jan.  10,  1910. 


Cream  Testing. 


79 


Cream-test  bottles.  Special  forms  of  bottles  have 
been  devised  for  testing  samples  of  cream  by  the  Bab- 
cock  test  by  Winton,  Bartlett,  and  by  various  manu- 
facturers. 

89.  The  Winton  cream  bottle.  The  cream-test  bottle 
devised  by  Winton,1  (fig.  32),  has  a  neck  of  the  usual 
length,  and  of  sufficient  width  to  measure 
30  or  50  per  cent,  of  fat.  The  scale  of 
the  neck  is  divided  into  parts  represent- 
ing one-half  of  one  per  cent, 
each,  but  readings  of  a  quarter 
of  a  per  cent,  can  easily  be  esti- 
mated. Such  readings  of 
cream  tests  are  sufficiently  ex- 
act for  most  commercial  pur- 
poses. This  form  of  cream  bot- 
tle will  be  found  very  conven- 
ient in  making  tests  of  com- 
posite samples  of  cream. 

Cream  test  bottles  of  a  small 
bore  are  greatly  to  be  preferred 
to  those  with  wide  necks  (fig. 
33),  since  they  permit  of  accu- 
rate readings  to  a  quarter  of  a  per  cent. 

Other  forms  of  cream-test  bottles  which 
allow  the  testing  of  50  or  55  per  cent,  cream 
have  been  placed  on  the  market  during  late 
years  by  some  manufacturers.     These  bot- 
FIG.  82a.    ties  (so-called  9-inch  bottles)  have  long  necks 
test  bottle.     an(j  require  especially  constructed,  large  and 

'Connecticut  experiment  station  (New  Haven),  bull.  117;  report 
1894,  p.  224. 


PIG.    32. 
The    30% 

cream 
bottle. 


test 


80 


Testing  Milk  and  Its  Products. 


deep  testers  (see  fig.  25).  These  machines  and  accom- 
panying bottles  have  of  late  been  adopted  for  cream 
testing  in  many  localities  where  farm  separator  cream 
is  delivered  to  the  creameries. 

90.  The  bulb-necked  cream  test  bottles  allow  the  teat 
ing  of  cream  containing  23  or  25  per  cent,  of  fat,  when  the 
usual  quantity  of  cream  (18  grams)  is  taken.  The  neck  is 
graduated  from  0  to  23  per  cent.,  and  in  some  cases  to  25  pei 
cent.,  the  graduation  extending  both  below  and  above  the  bulb. 
This  is  sometimes  an  inconvenience,  as  the  water  must  be  added 
carefully  so  that  the  lower  end  of  the  column  of  fat 
will  always  come  below  the  bulb,  in  the  graduated 
part  of  the  neck,  and  not  in  the  bulb  itself.-  Be 
ginners  are  especially  apt  to  lose  tests  when  this 
bottle  is  first  used,  for  the  reason  given.  It  is 
recommended  to  fill  these  bottles  with  the  first  por- 
tion of  hot  water  to  just  above  the  bulb,  so  that 
one  can  see  how  much  water  to  add  the  second 
time  in  order  to  bring  the  fat  within 
the  scale. 

Each  division  of  the  scale  on  these 
cream  bottles  represents  two-tenths 
of  one  per  cent,  of  fat,  as  in  case 
of  the  milk  test  bottles.  This  form 
of  bottle  is  no  longer  used  to  any 
extent,  as  it  has  been  largely  replaced 
by  the  different  forms  of  the  Winton 
Fio.  33.  cream-bottle. 

The  50%  91.  Scales  for  weighing  the 

bottle.  cream.    When  a  small,  delicate 

balance  is  used,  cream  can  be  weighed  rap- 
idly into  the  bottles.  Either  of  the  scales 
shown  in  the  accompanying  illustrations, 
(figs.  34-35),  will  be  found  sufficiently  ac- 
curate for  this  purpose;  a  small  scale  of  ^  50%!) 
this  kind  is  also  convenient  and  helpful  fe£tmbotrtiim 
in  testing  cheese,  butter  and  condensed  milk,  in  deter- 


Cream   Testing. 


81 


mining  the  strength  of  sulfuric  acid,  and  in  testing  the 
accuracy  of  test  bottles  and  pipettes. 

Cream  scales  similar  to  tnat  shown  in  fig.  35  permit 
the  weighing  of  two  or  four  samples  of  cream  at  a  time 
with  only  one  taring  of 
the  bottles,  which  great- 
ly facilitates  the  work  of 
testing  the  cream. 

In  testing  cream  by 
weighing,  the  test  bottle 
is  first  weighed  empty, 

FIG.  34.     Scales  used  for  weighing 

and  again  when  9  or  18         creflm  in  the  Babcock  test, 
grams  of  cream  have  been  placed  in  it;  the  difference 
between  the  two  figures  gives  the  weight  of  cream  taken 

for  the  test.  If  the  cream 
contains  less  than  30  per 
cent,  of  fat,  the  regular 
milk  test  bottle  can  also 
be  used  for  testing  the 
cream,  if  not  much  more 
than  5  grams  are  weighed 
out ;  if  more  cream  is 
taken,  or  if  this  is  richer 
than  30  per  cent.,  it  is 
advisable  to  use  special 
cream  bottles. 

The  operator  should  be 
FIQ.  35.   Torsion  balance  used  for    careful  in  weighing  the 

weighing  cream  In  the  Babcock  test.    cream   ^    ^   ^   ^    Qn 

the  outside  of  the  test  bottle.     If  less  than  18  grams 
of  cream  has  been  weighed  into  the  bottle  sufficient 


82  Testing  Milk  and  Its  Products. 

water  is  added  to  the  balance  to  make  the  total  vol- 
ume about  18  cc.  The  usual  quantity  of  acid  (17.5  cc.) 
is  then  added,  and  the  test  completed  in  the  ordi- 
nary manner.  The  reading  of  the  amount  of  fat  in 
the  neck  of  the  test  bottle  will  not  show  the  correct 
per  cent,  of  fat  in  the  cream  unless  exactly  18  grams  are 
weighed  out.  If  less  than  this  weight  was  taken  the 
per  cent,  of  fat  in  the  cream  tested  is  obtained  by  multi- 
plying the  reading  by  18,  and  dividing  the  product  by 
the  weight  of  cream  taken. 

EXAMPLE:     Weight  of  cream  tested,  5.2  grams;  reading  of  col- 
umn of  fat  *)  9.8, 2)  9.7,  average  9.75;  per  cent,  of  fat  in  the  cream 


It  is  very  convenient  to  weigh  out  18  grams  of  cream 
(or  9  grams)  so  that  the 
readings  may  be  taken  di- 
rectly from  the  neck  of  the 
bottle.  The  smaller  the  quan- 
tity of  cream  taken  for  a 
sample,  the  greater  is  the 
error  introduced  by  inaccu- 
rate weighings  or  readings. 
The  result  is  rendered  more 
accurate  if  two  or  three  tests 
of  a  sample  are  made,  and 
the  readings  averaged. 

913.  The  hydrostatic  bal- 
ance is  a  convenient  device 
for  weighing  cream  and 
other  dairy  products  to  be 
tested  by  the  Babcock  test 
(§ee  ng.  35a).'  This  balane, 

Wisconsin   exp.    station,    bull.    195 


Cream   Testing.  S3 

is  built  on  the  same  principle  as  a  lactometer :  it  is  pro- 
vided with  a  pan  on  the  top  of  the  stem,  on  which  the 
test  bottles  and  the  weights  are  placed.  When  put  into 
water  the  instrument  is  balanced  to  a  certain  point 
with  empty  test  bottles  and  weights  on  the  pan;  the 
weights  are  then  removed  and  sufficient  cream  added 
to  the  test  bottle  by  means  of  a  pipette  to  sink  it  to 
the  same  point  as  before. 

The  special  advantages  of  the  balance  are  that  there 
are  no  bearings  to  rust  and  become  dull;  it  is  durable, 
inexpensive  and  sensitive,  and  with  careful  handling 
will  remain  sensitive  indefinitely.  The  balance  can  be 
made  large  enough  to  weigh  a  number  of  bottles  at  a 
time,  as  is  the  case  with  some  of  the  cream  scales  on 
the  market. 

92.  Measuring  cream  for  testing.  Where  a  special 
cream  scale  or  a  small  balance  is  not  available,  fairly 
satisfactory  results  may  be  obtained  with  cream  of  low 
or  average  quality  by  measuring  out  the  sample  with 
a  17.6  pipette  and  correcting  the  results  as  indicated 
below.  One  of  the  cream  test  bottles  or  a  common  milk 
test  bottle  may  be  used  for  this  purpose.  The  table 
on  p.  77  shows  that  a  17.6  cc.  pipette,  in  the  case  of 
cream  fresh  from  the  separator,  containing  less  than 
25  per  cent,  of  fat,  will  deliver  only  17.2  grams  of 
cream,  that  is,  the  results  will  be  --^p  =1.1  per  cent,  too 
low.  In  the  same  way  in  case  of  40  per  cent,  cream, 
only'  16.3  grams  of  cream  would  be  delivered,  and  the 
results  therefore  3.8  per  cent,  too  low.  When  the  cream 
has  been  ripened  or  is  thick,  less  cream  would  be  deliv- 
ered than  the  amounts  given,  and  the  error  introduced 
by  measuring  out  the  samples  correspondingly  increased. 


84  Testing  Milk  and  Its  Products. 

A  table  of  correction  for  testing  such  cream  by  meas- 
uring the  samples  has  been  prepared  by  Prof.  Eckles, 
formerly  of  Iowa  experiment  station.1 

Approximately  correct  results  may  be  obtained  in 
testing  thin  cream  by  using  an  18  cc.  measuring  pipette ; 
to  avoid  the  expense  and  trouble  of  using  two  different 
pipettes,  one  for  milk  and  one  for  cream,  a  pipette  with 
two  marks  on  the  stem,  at  17.6  cc.  and  18  cc.,  has  been 
placed  on  the  market,  the  former  mark  being  used  when 
milk  is  tested,  and  the  latter  for  cream.  It  should  be 
borne  in  mind,  however,  that  such  pipettes  can  only  be 
used  in  the  case  of  sweet  cream  of  average  richness, 
and  will  then  give  only  approximately  correct  results 

93.  Use  of  milk  test  bottles.  Cream  may  be  tested 
by  emptying  a  17.6  cc.  pipetteful  into  two  or  more  milk 
test  bottles,  dividing  the  sample  about  equally  between 
the  bottles  and  filling  the  pipette  with  water  once  or 
twice,  which  is  then  in  turn  divided  about  equally  be- 
tween the  test  bottles ;  the  per  cent,  of  fat  in  the 
cream  is  found  by  adding  the  readings  obtained  in 
each  of  the  bottles.  The  cream  and  the  water  must  be 
mixed  before  the  acid  is  added. 

This  method  does  away  with  the  error  incident  to  the 
adhesion  of  cream  to  the  side  of  the  pipette,  but  not 

» Press  bull,  dated  August,  1901.  Some  creameries  heat  the  samples 
of  cream  in  a  water  bath  to  about  140°  F.  before  the  test  samples  are 
measured  out  by  means  of  a  17.6  cc.  pipette.  This  increases  the  fluidity 
of  the  cream  and  causes  less  to  adhere  to  the  pipette.  The  Vermont  ex- 
periment station  (report  16,  pp.  191-6)  found  in  examining  this  method 
that  It  did  not  yield  satisfactory  results  in  the  case  of  cream  of  dif- 
ferent richness  and  recommends  that  cream  be  weighed  when  accurate 
tests  are  desired. 


Cream  Testing.  85 

that  due  to  the  IOAV  specific  gravity  of  the  cream, 
and  the  results  obtained  will  therefore  be  too  low. 

The  dilution  of  the  cream  with  water  in  the  test  bot- 
tles not  only  makes  it  possible  to  bring  into  the  bottle 
all  the  cream  measured  out,  but  also  insures  a  clear  test. 
If  ordinary  cream  is  mixed  with  the  usual  quantity 
of  sulfuric  acid  used  in  the  Babcock  test,  a  dark-colored 
fat  will  generally  be  obtained,  while  the  cream  diluted 
with  an  equal  or  twice. its  volume  of  water,  when  mixed 
with  the  ordinary  amount  of  acid,  will  give  a  light  yel- 
low, clear  column  of  fat,  which  will  allow  of  a  very 
distinct  and  sharp  reading. 

The  number  of  bottles  to  be  used  for  testing  a  sam- 
ple of  cream  by  this  method  must  be  regulated  by  the 
richness  of  the  cream.  If  the  sample  probably  contains 
20  per  cent,  or  more,  a  pipetteful  should  be  divided 
about  equally  between  three  milk  test  bottles,  and  two- 
thirds  of  a  pipetteful  of  water  is  added  to  each  bottle. 
If  the  cream  contains  less  than  20  per  cent,  of  fat,  it 
will  only  be  necessary  to  use  two  milk  test  bottles,  divid- 
ing the  pipetteful  between  these,  and  adding  one-half 
of  a  pipetteful  of  water  to  each  bottle. 

By  using  cream  test  bottles  (89),  more  accurate  tests 
may  be  obtained  in  case  of  cream  containing  as  much 
as  25  per  cent,  of  fat,  by  dividing  one  pipetteful  be- 
tween two  bottles,  rinsing  half  a  pipette  of  water  into 
each  one,  than  by  adding  all  the  cream  to  one  bottle 
without  rinsing  the  pipette,  for  reasons  apparent  from 
what  has  been  said  in  the  preceding. 


86  Testing  Milk  and  Its  Products. 

94.  Use  of  a  5  cc.  pipette.  When  the  cream  is  in  good  con- 
dition for  sampling,  satisfactory  results  can  also  be  obtained  by 
the  use  of  a  5  oc.  pipette,  provided  great  care  is  taken  in  mix- 
ing the  cream  before  sampling;  5  cc.  of  cream  are  measured  into 
a  milk  test  bottle,  and  two  pipettefuls  of  water  are  added.  In 
this  way  all  the  cream  in  the  pipette  is  easily  rinsed  into  the 

test  bottle.  The  readings  multiplied  by  f  =3.6  will  give  the 
per  cent,  of  fat  in  the  cream.  <  If  the  specific  gravity  of  the 
cream  tested  varies  appreciably  from  1,  corrections  should  be 
made  accordingly;  e.  g.,  if  the  specific  gravity  is  1.02,  the  fac 

18 


tor  should  read 


=3.53;    if   .95, 


=3.79,  etc. 


=—30 
E— 28 
•E— 26 
=—24 


c  — 


95-  Proper  readings  of  cream  tests.  The  accom- 
panying illustration  (fig.  36),  shows  the  proper  method 
of  reading  the  fat  column  in  cream 
tests;  readings  are  taken  from  a  to  c, 
not  to  6  or  to  d,  when  readings  are 
made  at  140°  F.1 

No  special  precautions  other  than 
those  required  in  testing  milk  have  been 
found  necessary  in  testing  cream,  ex- 
cept that  it  is  sometimes  advisable  not 
to  whirl  the  test  bottles  in  the  centri- 
fuge at  once  after  mixing,  but  to  let  the 
cream-acid  mixture  stand  for  a  while, 
until  it  turns  dark  colored.  At  first, 
the  mixture  of  cream  and  acid  is  much 
lighter  colored  than  that  of  milk  and 
PIG.'  36.  Measur-  acid,  owing  to  the  smaller  proportion-  of 
!ngt?ee  naeckCOofma  solids  not  fat  contained  in  the  cream. 

cream  bottle.  Read-          m,        •,.       .  ,    ,  ,1,1        »    .    • 

ing  should  be  made       The  liquid  beneath  the  fat  in  a  com- 

from  a  to  c,  not  to       i    .    j    .  »  •  .  •  -n 

ft  or  to  d.  pleted  test  of  cream  is  sometimes  milky 

JThe  size  of  the  meniscus  is  magnified  in  this  cut.    A  study  of  the 
meniscus  formed  in  bottles  with  narrow  or  wide  necks,  and  its 


Cream   Testing.  87 

and  the  fat  appears  white  and  cloudy,  making  an  exact 
reading  difficult.  Such  defects  can  usually  be  over- 
come by  placing  the  test  bottles  in  hot  water  for  about 
ten  minutes  previous  to  the  whirling,  or  by  allowing  the 
fat  to  crystallize  (which  is  done  by  cooling  the  bottles 
in  cold  water  after  the  last  whirling)  and  remelting 
it  by  placing  the  bottles  in  hot  water. 

The  error  due  to  the  expansion  of  the  fat  in  case  of 
excessively  hot  turbine  testers  having  no  openings  in 
the  cover  as  mentioned  on  p.  36,  is  especially  noticeable 
in  cream  testing,  where  it  may  amount  to  one  per  cent, 
or  more.  In  order  to  obtain  correct  results  with  such 
testers,  the  hot  cream  test  bottles  must  be  placed  in 
water  at  about  140°  F.  for  some  minutes  before  the 
results  are  read  off. 

The  subject  of  different  methods  of  reading  cream 
tests  have  been  studied  by  Webster  and  Gray,1  who 
conclude  that  correct  results  are  obtained  by  taking 
readings  at  120°  P.,  from  the  bottom  to  the  extreme 
top  of  the  fat  column,  deducting  four-fifths  of  the 
depth  of  the  meniscus  from  this  result  and  adding  .2 
per  cent,  to  the  figure  thus  obtained. 

96.  Eliminating  the  meniscus  in  cream  tests.  The 
uncertainty  concerning  the  exact  point  at  which  the 
meniscus  of  the  fat  column  should  be  read  in  cream 
tests  has  been  removed  by  the  use  of  certain  liquids 
which  do  not  mix  with  fat  but  which  when  dropped  on 

bearing  on  the  results  of  cream  tests  is  given  in  bulletin  58.  Bur. 
An.  Ind.,  U.  S.  Dept.  of  Agriculture,  where  a  discussion  of  the 
influence  of  different  temperatures  on  readings  of  cream  tests 
will  also  be  found  (see  96). 

1  Bull.  58,  Bur.  An.  Ind.,  U.  S.  Dept.  of  Agriculture.  See  also  Mass, 
rept.,  1909,  p.  142. 


88 


Testing  Milk  and  Its  Products. 


top  of  the  fat  column  change  the  curved  surface  of  the 
meniscus  into  a  straight  line.  Amyl  alcohol,  fat-satur- 
ated alcohol  and  glymol  have  been  suggested  for  this 
purpose. 

Amyl  alcohol  colored  red  by  fuchsin  was  suggested 
by  Eckles.1  This  may  dissolve  some  of  the  fat  and  thus 
cause  a  slightly  low  reading.  Fat-saturated  alcohol1 
largely  overcomes  this  objection.  It  is  made  by  adding 
about  a  teaspoonful  of  butter  to  six  ounces  of  dena- 
tured or  wood  alcohol  in  a  stoppered  bottle.  This  is 
warmed  slightly  and  shaken  until  the  alcohol  does  not 
dissolve  any  more  of  the  fat.  A  small  amount  of 
coloring  matter  may  be  added  to 
this  solution  to  further  facilitate 
the  reading.  The  use  of  glymol*  or 
white  mineral  typewriter  and  sew- 
ing machine  oil  was  suggested  by 
Hunziker  for  reading  cream  tests, 
after  an  exhaustive  study  of  the 
subject.  Glymol  may  be  colored 
with  ajkanet  root  which  can  be  ob- 
tained from  a  druggist.  One  ounce 
of  alkanet  root  will  color  one  quart 
of  gtymol;  this  is  done  by  placing 
ltlduafco°ho^isyamorr  a  sraa11  cheese  cloth  bag  filled  with 
tSe'  iK.TOff1?  the  alkanet  r°ot  in  the  bottle  of 

glymol  for  one  or  two  days. 

A  convenient  way  of  adding  alcohol,  glymol,  etc.,  to 
the  fat  column  after  completing  a  test  is  to  insert  a 


Pig.     36a.      Showing- 


1  N.  Y.  Produce  Review,  Aug.  8,  1908. 

1  Wis.  Expt.  Sta.  Bui.  195,  p.  6. 

•iMrdne.  Ind.,  Expt.  Sta.  Bui.  145,  vol.  XV.  p. 


Cream  Testing.  89 

glass  tube  through  a  cork  or  stopper  of  a  bottle  con- 
taining the  liquid;  by  placing  a  finger  on  the  top 
of  the  tube  a  small  portion  may  be  transferred  from 
the  bottle  to  the  top  of  the  fat  column.  By  the  use  of 
either  of  the  liquids  mentioned  the  meniscus  in  cream 
tests  disappears,  giving  a  straight  line  at  the  top  as 
well  as  the  bottom  of  the  fat  column  and  thus  making 
it  possible  to  obtain  exact  readings  of  the  per  cent,  of 
fat  in  any  sample  of  cream. 


Question*. 

1.  Give  three  reasons  for  weighing  cream  for  testing. 

2.  How  does  the  richness  of  the  cream  influence  its  weight? 

3.  What  is  the  weight  of  one  gallon  of  cream  testing  10,  30, 
or  50%  fat? 

4.  Describe  at  least  three  forms  of  cream  test  bottles. 

5.  What  purpose  does  the  bulb  in  the  cream-test  bottle 
serve? 

6.  Between  what  points  should  the  cream  fat  column  be  read! 

7.  If  cream  was  erroneously  weighed  into  a  test  bottle  as  9.3 
gr.  instead  of  10  gr.,  what  error  would  this  cause  on  a  sample 
testing    33%    fat? 

8.  Mention  a  few   important  points  in  the  construction  of  c 
cream  test  bottle. 

9.  If  12.5  gr.  cream  give  a  reading  of  18.5,  what  is  the  «*• 
rcct  test  of  the  sample? 

10.  If  7.2  gr.  of  cream  give  a  reading  of  6.4,  what  is  the  cor 
rect  test  of  the  sample? 

11.  If  the  fat  in  a  cream  test  is  read  as  28%  at  a  temperature 
of   180°   F.,  what  is  the  correct  test? 

12.  If  at  the  end  of  a  full  day's  run  4,280  Ibs.  of  milk  had 
been  received,  testing  3.95  per  cent.,  and  535  Ibs.  of  cream  test- 
ing 34.5  per  cent,   fat;   how  much  fat   (a)    in   the  whole  milk; 
(b)    in   the  cream;    (c)    in   the  skim  milk?    (d)    what  would  be 
the  test  of  the  skim  milk,    (e)   how  many  pounds  of  skim  milk 
would  there  be;  and   (f)   what  would  be  the  per  cent,  of  cream 
from  the  milk? 


CHAPTER  V.. 
BABCOCK  TEST  FOR  OTHER  MILK  PRODUCTS 

97.  Skim  milk.  Each  division  on  the  scale  of  the 
neck  of  the  regular  Babcock  test  bottle  represents  two- 
tenths  of  one  per  cent.  (44).  When  a  sample  of  skim 
milk  or  butter  milk  containing  less  than  this  per  cent, 
of  fat  is  tested,  the  estimated  amount  is  expressed  by 
different  operators  as  one-tenth,  a  trace,  one-tenth  trace, 
or  one-  to  five-hundredths  of  one  per  cent.  Gravimetric 
chemical  analyses  of  skim  milk  have,  however,  shown 
that  samples  which  give  only  a  few  small  drops  of  fat 
floating  on  the  water  in  the  neck  of  the  test  bottle,  or 
adhering  to  the  side  of  the  neck,  generally  contain 
one-tenth  of  cne  per  cent,  of  fat,  and  often  more.  Samples 
of  skim  milk  containing  much  less  than  one-tenth  of  a 
per  cent,  of  fat  are  very  rare,  and  it  is  doubtful  whether 
a  sample  of  separator  skim  milk  representing  a  run 
of,  say  5000  Ibs.  of  milk,  will  ever  show  less  than 
five-hundredths  of  one  per  cent,  of  fat.  Under  ordi- 
nary factory  conditions,  few  separators  will  deliver 
skim  milk  containing  under  one-tenth  of  one  per  cent, 
of  fat,  when  the  sample  is  taken  from  the  whole  day's 
run.  This  must  he  iM.usidered  ;i  satisfactory  separation.' 

1  For  comparative  analyses  of  separator  skim  milk  by  the  gravi- 
metric method  and  by  the  Babcock  test,  see  Wis.  exp.  station  bull.  52 
and  rep.  XVII,  p.  81 ;  Conn.  (Storrs)  exp.  station,  bull.  40 ;  Utah  exp. 
station,  bull.  96.  See  also,  Woll,  Testing  Skim  Milk  by  Babcock  Test, 
In  Country  Gentleman,  April  26,  1902.  The  results  obtained  by  the  use 
of  the  Cottllol)  method  have  shown  that  ether-extrartlon  methods,  ns 


Babcock  Test  for  other  Milk  Products.  91 

98.  The  reason  why  the  Babcock  test  fails  to  show  all 
the  fat  present  in  skim  milk  must  be  sought  in  one  or 
two  causes:  a  trace  of  fat  may  be  dissolved  by  the  sul- 
furic  acid,  or  owing  to  the  minuteness  of  the  fat  glob- 
ules of  such  milk  they  are  not  brought  together  in 
the  neck  of  the  bottles  at  the  speed  used  with  the  Bab- 
cock test.  The  latter  cause  is  the  more  likely  explana- 
tion. If  a  drop  of  the  dark  liquid  obtained  in  a  Bab- 
cock bottle  from  a  test  of  whole  milk  be  placed  on  a 
slide  under  the  microscope,  it  will  be  seen  that  a  fair 
number  of  very  minute  fat  globules  are  found  in  the 
liquid.  These  globules  are  not  brought  into  the  column 
of  fat  in  the  neck  of  the  bottle  by  the  centrifugal  force 
exerted  in  the  Babcock  test,  even  if  the  bottles  are 
whirled  in  a  turbine  tester  in  which  they  are  heated 
to  200°  F.  or  higher  (see  71)  ;  the  loss  of  the  fat  con- 
tained in  these  fine  globules  is  compensated  for,  in  the 
testing  of  whole  milk,  by  a  liberal  reading  of  the 
fat  column,  this  being  taken  from  the  bottom  of  the 
fat  to  the  top  of  the  upper  meniscus  (see  p.  35)  ; 
in  some  separator  skim  milk,  on  the  other  hand,  not 
enough  fat  remains  to  completely  fill  the  neck,  and  the 
reading  must  therefore  be  increased  by  at  least  five- 
hundredths  of  one  per  cent. 

It  follows  from  what  has  been  said  that  tests  of  skim 
milk  showing  but  a  drop  or  two  of  fat  in  the  neck  of 
the  test  bottles  on  completion  of  the  test,  generally  in- 
dicate inefficient  work  of  the  centrifugal  tester  or  of 

well  as  the  Babcock  test,  give  too  low  results  with  dairy  by-products 
low  tn  fat,  like  skim  milk,  butter-milk,  etc.  The  Gottlieb  method  for 
this  reason  has  been  adopted  by  European  chemists  as  a  standard  for 
analysis  of  these  products.  (See  254 1. 


92  Testing  Milk  and  Its  Products. 

the  operator,  or  of  both.  The  test  should  be  repeated 
in  such  cases,  using  more  acid  and  whirling  for  full 
five  minutes.  Separator  skim  milk  should  be  allowed 
to  stand  10  to  15  minutes  before  the  sample  is  taken  so 
as  to  allow  the  air  to  escape. 

In  order  to  bring  as  much  fat  as  possible  into  the 
neck  of  the  bottles  in  testing  skim  milk,  it  is  advisable 
to  add  somewhat  more  acid  than  when 
whole  milk  is  tested,  viz.,  about  20  cc., 
and  to  whirl  the  bottles  at  full  speed  for 
at  least  five  minutes,  keeping  the  tester  as 
hot  as  possible  the  whole  time.1  The  read- 
ings must  be  taken  as  soon  as  the  whirl- 
ing is  completed,  since  owing  to  the  con- 
traction of  the  liquid  by  cooling,  the  fat 
will  otherwise  adhere  to  the  inside  of  the 
neck  of  the  test  bottle  as  a  film  of  grease 
which  cannot  be  measured  by  the  scale. 

99.  The  double-necked  test  bottle, 
(fig.  37),  suggested  by  one  of  us,2  is  made 
especially  for  measuring  small  quantities 
of  fat  and  gives  fairly  satisfactory  results 
in  testing  skim  milk  and  butter  milk. 
Generally,  each  division  of  the  scale  on 
these  bottles  represents  five-hundredths  FIG  37  The 
of  one  per  cent.,  and  the  marks  are  so 


apart   that   the  small  fat  column    can  beca\?ed(8°n^etohi- 
easily  estimated  to   single  hundredths   of  bottle).  B>  * 

1  See  Wis.  exp.  station,  report  17,  p.  81. 

'First  constructed  by  Mr.  J.  J.  Nnssli.nnmer,  of  Illinois;  now  manu- 
factured by  various  flrron. 


Babcock  Test  for  other  Milk  Products.  93 

one  per  cent.  In  the  first  forms,  now  out  of  use,  the 
neck  was  graduated  to  hundredths  of  one  per  cent. 

The  value  of  the  divisions  of  the  scale  on  the  double- 
necked  test  bottles  has  been  a  subject  of  considerable 
discussion,  and  various  opinions  have  been  expressed 
whether  they  show  one-tenth  or  one- twentieth  (.05)  of 
one  per  cent,  of  fat.  By  calibration  with  mercury  the 
value  of  the  divisions  will  be  found  to  be  .05,  or  one- 
twentieth,  of  one  per  cent.,  but  as  shown  above,  the  re- 
sults obtained  in  using  the  bottles  for  separator  skim 
milk  generally  come  at  least  .05  per  cent,  too  low,  so 
that,  practically  speaking,  each  division  may  be  taken 
to  show  one-tenth  of  one  per  cent.,  if  the  fat  fills  only 
one  division  of  the  scale  or  less.1 

The  double-necked  bottle  is  very  convenient  for  the 
testing  of  separator  skim  milk,  thin  butter  milk  and 
whey.  The  milk,  acid  and  water  are  added  to  the  bottle 
through  the  filling-tube;  the  mixing  of  milk  and  acid 
must  be  done  with  great  care,  so  that  none  of  the  con- 
tents is  forced  into  the  fine  measuring  tube  and  lost;  it 
is  best  to  add  half  of  the  acid  first  and  mix  it  with  the 
milk,  and  then  add  the  rest.  When  the  fat  is  in  the 
lower  end  of  the  measuring  tube,  it  can  be  forced  into 
the  scale  by  pressing  with  the  finger  on  the  top  of  the 
side  tube. 

In  placing  the  double-necked  bottles  in  the  tester  they 
should  be  put  with  the  filling  tube  toward  the  center,  so 
as  to  avoid  any  of  the  fat  being  caught  between  this 
tube  and  the  side  of  the  bottle  when  it  resumes  a  verti- 
cal position. 

i  AVisc.  exp.  sta.,  bull.  52;  Penna.  exp.  sta.,  repot-t  1896,  p.  221. 


94 


Testing  Mtik  and  Its  Products. 


This  test  bottle  is  more  fragile  and  expensive  than 
the  ordinary  Babcock  bottles,  and  must  be  carefully 
handled;  it  is  now  generally  made  of  heavier  glass 
than  formerly,  and  this  form  is  to  be  highly  recom- 
mended.1 (See  fig.  38.) 

100.  The    double-size    skim    milk    bottle     which  was  the 
first  one  recommended  for  the  testing   of  skim  milk,   is  of  no 
particular  value.     It  is  difficult  to  obtain  a  thorough  mixture  of 
the  milk  and  the  acid  in  these  bottles,  and  the  tests  invariably 
come  too  low,  more  so  than  with  the  regular  Babcock  bottles  or 
double-necked   skim   milk   bottles,   for   reasons 

that  are  readily  seen. 

101.  Buttermilk    and    whey.      The 
testing  of  buttermilk  by  the  Babcock 
test  offers  no  special  difficulties  if  the 
special  directions  for  testing  skim  milk 
are  followed ;  what  has  been  said  in  re- 
gard to  tests  of  separator  skim  milk  is 
equally  true  in  case  of  this  by-product. 
Whey  contains  only  a  small  quantity 
of  solids  not  fat,  viz.,  less  than  7  per 
cent.   (27),  and  the  mixing  with  acid 
and  the   solution   of   the   whey   solids 
therein    is    therefore    readily    accom- 
plished ;  the  acid  solution  is  of  a  light 
reddish  color,  turning  black  but  very 
slowly. 

102.  Butter.    Butter  is  not  so  easily  tested  as  other 
dairy  products,  both  because  of  the  difficulties  in  ob- 
taining a  fair  sample,  and  on  account  of  the  high  per- 
centage of  fat  it  contains.    Butter  is  a  mechanical  mix- 

*A  double-necked  copper  test  bottle  with  a  detachable  graduated 
rlass  neck  was  designed  and  tried  by  one  of  us  a  few  years  ago,  but  It 
was  not  found  to  possess  any  special  advantage  over  .the  glass  bottle. 


FIG.  38. 

The  double-bore 

kim   milk  bottle. 


Babcock  Test  for  other  Milk  Products.  95 

ture  of  water,  curd,  and  salt,  with  butter-fat;  and  the 
water  or  brine  is  so  easily  pressed  out  that  great  care 
must  be  taken  to  get  the  same  amount  of  water  in  the 
small  portion  to  be  tested  as  exists  in  the  lot  of  butter 
sampled. 

Sampling  butter.  Small  portions  of  butter  are  taken 
with  a  butter  trier  or  a  knife  from  different  parts  of 
the  tub,  package,  or  churning  of  butter  to  be  tested. 
These  small  portions  (preferably  about  200  grams  in 
all)  are  placed  in  a  wide-necked  bottle  or  jar  which  is 
securely  stoppered  and  placed  in  warm  water  until  the 
butter  melts.  The  jar  is  then  shaken  vigorously  in  order 
to  obtain  a  thorough  mixing  of  the  various  components 
of  the  butter,  and  placed  in  cold  water.  As  the  butter 
ccols,  the  jar  must  be  shaken  repeatedly  until  the  butter 
either  solidifies  or  becomes  of  a  thick  creamy  consist- 
ency. From  this  sample  small  portions  may  be  taken 
for  testing. 

It  is  not  always  necessary  to  prepare  a  sample  of 
butter  for  testing  in  the  manner  described.  If  the  but- 
ter contains  no  loose  drops  of  brine  on  the  freshly-cut 
surface,  a  sample  for  testing  can  be  taken  directly  from 
the  package.  The  operator  must  use  his  judgment  in 
regard  to  the  necessity  of  preparing  a  special  sample  in 
each  case. 

Scales  for  weighing  butter.  In  testing  butter  it  is 
necessary  to  weigh  the  amount  taken  for  a  test  very 
accurately.  Scales  sensitive  to  less  than  .05  gram  should 
be  used,  as  a  difference  of  .1  gram  in  weight  has  a  value 
of  1.0  per  cent,  in  the  result  when  10  grams  of  butter 
are  tested.  Slow-working  scales  with  rusted  bearings 
are  worthless  for  testing  butter.  The  scales  should 


96  Testing  Milk  and  Its  Products. 

always  be  balanced  before  being  used  and  the  weights 
kept  bright  and  clean. 

Carelessness  in  weighing  may  be  the  cause  of  very 
inaccurate  results,  and  the  importance  of  a  sensitive 
scale  cannot  be  over-estimated.  Scales  with  a  graduated 
side  beam  are  preferable  to  those  that  require  the  use 
of  small  weights.  Scales  sensitive  to  .01  gram  are  now 
on  the  market,  which  permit  of  20  to  50  grams  of  butter 
being  weighed  out  for  testing.1 

103.  Fat  in  butter.  The  Babccck  test  can  be  used 
with  only  a  fair  degree  of  accuracy  for  estimating  the 
per  cent  of  fat  in  butter,  by  weighing  9  grams  of  butter 
into  a  test  bottle  graduated  to  measure  50  per  cent.  fat. 
About  10  cc.  of  hot  water  is  added  to  the  butter,  and 
17.5  cc.  of  sulfuric  acid  of  one-half  the  strength  used  in 
milk  testing.  Mix  the  butter  and  acid  until  the  curd 
is  all  dissolved,  add  hot  water  to  bring  the  fat  into 
the  neck  of  the  test  bottle  and  whirl  in  a  centrifuge. 
When  a  clear  separation  of  the  fat  is  obtained  the  test 
bottle  is  placed  in  water  of  140°  F.  up  to  near  the  top 
of  the  neck  and  after  standing  a  few  minutes  in  this 
water  the  fat  column  is  read  off ;  the  reading  multiplied 
by  2  gives  the  per  cent,  of  fat. 

Fairly  accurate  results  can  only  be  obtained  by  taking 
great  care  in  all  the  manipulations,  especially  in  weigh- 
ing the  butter  and  in  reading  the  fat  at  the  proper  tem- 
perature. Small  errors  in  making  tests  have  a  marked 
influence  on  the  results,  because  the  butter  fat  is  such  a 
large  per  cent  of  the  butter.  Tests  should  always  be 
made  in  duplicate,  and  even  then  results  are  only 
approximately  correct.2 

1  See  bull.  154,  Wisconsin  exp.  sta.,  p.  10. 

*  Special  bottles  for  testing  butter  for  Its  fat  content  have  been  put 


Babcock  Test  for  other  Milk  Products.  97 

104.  Cheese.    Cheese  can  be  easily  tested  by  the  Bab- 
cock  test  if  a  small  scale  (fig.  58b)  is  at-Jhand  for  weigh- 
ing the  sample;  the  results  obtained  will  furnish  accu- 
rate information  as  to  the  amount  of  fat  in  the  cheese, 
provided   good    judgment   and    exactness   are   used    in 
sampling   and  weighing   the  cheese.       For    inspection 
purposes  the  rind  may  be  rejected,   but  for  investi- 
gations,   where    the    absolute  quantity    of  fat    in    the 
cheese  is  required,  the  rind  shouLl  be  included  in  the 
sample.1     The  following  method  of  sampling  cheese  is 
recommended. 

105.  Draw  a  plug  from  a  sound  portion  of  the  cheese 
with  a  cheese  trier;  this  should  be  taken  at  a  point  that 
is  not  near  the  rind,  a  cut  surface  of  the  cheese,  a  de- 
fective spot  or  an  old  trier  hole.  Cut  off  the  top  one-half 
inch  of  the  trier  plug  and  replace  it  in  the  trier  hole  to 
protect  the  cheese ;  then  cut  the  plug  of  cheese  length- 
wise into  four  pieces  and  slip  two  of  these  into  the  neck 
of  a  cream  test  bottle  which  has  been  previously  weighed 
empty. 

After  adding  8  to  10  grams  of  the  cheese  in  this  way 
the  test  bottle  should  be  weighed  again  and  the  exact 
weight  of  cheese  taken  for  testing  is  obained  by  sub- 
traction. 

10  ec.  of  boiling  water  is  then  added  to  the  test  bottle 
by  using  a- wide  tipped  pipette,  and  acid  is  added  im- 
mediately in  portions  of  about  1  cc.  each  at  first,  shak- 
ing the  bottle  for  a  second  after  each  addition  of  acid. 

on  the  market,  e.  g.,  the  Wagner  Butter  Test  Bottle  and  the  form  Bug- 
srested  by  H.  R.  Wright,  given  in  the  18th  report  of  the  Iowa  Stnt«- 
Dairy  Commissioner,  1904,  p.  40. 

1TL   S.   Dept.   of  Agriculture,   Chemical    Division,  bull.   46,   p.   37. 

7 


98  Testing  Milk  and  Its  Products. 

This  method  of  adding  the  acid  gradually  to  the  hot 
water  and  cheese  in  the  test  bottle  produces  a  temper- 
ature high  enough  to  melt  the  cheese  immediately  so 
that  the  test  bottle  may  be  placed  in  the  centrifuge  at 
once  and  the  fat  separated  and  measured  in  the  usual 
way  for  testing  cream.1 

The  per  cent,  of  fat  in  the  cheese  is  obtained  by  mul- 
tiplying the  reading  of  the  fat  column  by  18  and  divid- 
ing the  product  by  the  weight  of  cheese.  The  weighing 
of  the  cheese  and  the  reading  of  the  fat  must  be  done 
very  carefully,  since  any  error  introduced  is  more  than 
trebled  in  calculating  the  per  cent,  of  fat  in  the  cheese. 

106.  Condensed  milk.  The  per  cent,  of  fat  in  un- 
sweetened condensed  milk  can  be  obtained  by  weighing 
about  9  grams  into  a  test  bottle  and  proceeding  in  ex- 
actly the  same  way  as  given  under  testing  of  cheese. 
It  is  not  necessary  to  warm  the  condensed  milk  in  the 
test  bottles,  since  this  is  readily  dissolved  in  water. 
Enough  water  should  be  added  to  make  the  total  volume 
of  liquid  in  the  bottles  15  to  18  cc. 

If  a  scale  is  not  available  for  weighing  the  sample, 
fairly  accurate  results  may  be  obtained  by  diluting  the 
condensed  milk  with  water  (1:3),  and  completing  the 
test  in  the  ordinary  manner.  When  this  is  done,  the 
results  must  be  corrected  for  the  dilution  which  the 
sample  received. 

TTunxiker2    recommends    adding    hot,    dilute    sulfurk- 

•?i<-i«l  solution  after  the  first  whirling, 'in  the  analysis  of 

unsweetened  condensed  milk  (sulfuric  acid  and  water, 

1  See  also  Sammis,  Journ.  Ind.  and  Eng.  Chem.,  I,  p.  604. 
1  Ind.  erpt.  sta.,  bull.  134. 


Babcock  Test  for  other  Milk  Products.  99 

1:1).     He  finds  that  this  aids  in  giving  a  clear  separa- 
tion of  the  fat  and  obtaining  satisfactory  results.1 

107.  Sweetened    condensed    milk.      The   testing   of 
sweetened  condensed  milk  presents  peculiar  difficulties, 
whether  it  is  to  be  tested  by  the  Babcock  test  or  by 
chemical  analysis.     It  may,  however,  be  readily  tested 
by  the  Babcock  test  by  using  the  methods  given  for 
testing  ice  cream. 

The  Mojonnier  Tester.  This  is  an  apparatus  de- 
signed especially  for  determining  butter  fat  and  total 
solids  in  condensed  milk,  ice  cream,  milk  powder  and 
other  dairy  products.  It  is  based  on  the  Rose-Gottlieb 
method  (254).  The  manipulations  of  the  method  are 
much  facilitated,  and  the  time  required  for  making  the 
determinations  are  greatly  reduced,  by  the  use  of  this 
tester  which  includes  a  chemical  balance,  electric 
ovens,  hot  plates,  motors,  etc. 

108.  Ice   cream.     Methods   for   determining  the  per 
cent,  of  fat  in  ice  cream  have  been  worked  out  by 
Holm,2  Howard3  and  others.     On  account  of  the  ten- 
dency of  ice  cream  to  foam  when  melted,  it  should  be 
mixed  carefully  by  pouring  a  number  of  times  from  one 

lFor  analysis  of  unsweetened  condensed  milk,  see  also  Jr.  Ind.  and 
Eng.  Chem.,  1913,  pp.  131  and  168.  Good  results  may  be  secured  by 
adding  3  cc.  of  a  mixture  of  equal  parts  of  amyl  alcohol  and  C.  P. 
hydrochloric  acid  to  the  milk,  then  10  cc.  o£  C.  P.  sulfuric  acid,  and 
proceeding  as  given  above  (Amott). 

The  Gottlieb  method  gives  very  satisfactory  results  with  both  cheese 
and  condensed  milk  (see  254).  See  also  Jr.  Ind.  and  Eng.  Chem., 
1912,  p.  672.  For  method  of  analysis  of  desiccated  milk,  milk  powder, 
etc.,  see  ibid.,  1912,  p.  544. 

2  Report  Dept.  of  Health,  City  of  Chicago,  1906,  p.  50. 

s  Journ.  Am.  Chem.  Soc.,  1907,  p.  16.  Methods  of  analysis  of  ice 
<  roam  have  also  been  proposed  by  White,  (Penna.  exp.  sta.,  rept.  1910, 
p.  243),  Baird,  (N.  Y.  Prod.  Rer.,  Feby.  26,  1913),  and  Halvorsen. 
<Ir.  Ind.  and  Eng.  Chem..  5  (1913),  p.  403). 


100  Testing  Milk  and  Its  Products. 

vessel  into  another  and  instead  of  measuring  with  a 
pipette,  about  9  grams  are  poured  rapidly  into  a  cream- 
test  bottle  which  should  be  weighed  empty  and  again 
after  adding  the  ice  cream.  This  may  be  tested  by 
either  the  sulfuric-acid  or  the  nitric-acid  test. 

Sulfuric  acid  only  may  be  used  successfully  by  add- 
ing it  in  small  portions  after  about  10  cc.  of  warm 
water  has  been  added  to  the  ice  cream  in  the  test  bottle. 
The  amount  of  acid  required  is  shown  by  the  color  of 
the  mixture  which  becomes  dark  brown  as  the  portions 
of  acid  are  added  and  mixed  with  the  ice  cream.  When 
this  color  is  obtained,  further  action  of  the  acid  is 
stopped  by  adding  a  little  cold  water  to  the  mixture  in 
the  test  bottle  which  is  then  placed  in  a  centrifuge 
and  the  test  completed  in  the  usual  way. 

Holm  recommends  the  use  of  a  mixture  of  equal  parts 
of  hydrochloric  and  glacial  acetic  acid,  in  place  of  sul- 
furic  acid,  as  the  latter  may  char  the  sugar  in  the  ice 
cream,  thus  giving  difficulty  in  reading  the  results. 
Nine  grams  of  either  the  frozen  or  melted  sample  are 
weighed  into  a  Babcock  milk  bottle,  which  is  then 
filled  almost  to  the  neck  with  the  mixture  of  the  two 
acids  given.  This  is  heated  for  a  few  minutes  until 
black,  when  the  bottle  is  whirled  in  the  tester  and 
water  added  to  bring  the  fat  column  within  the  grad- 
uations of  the  neck,  as  in  the  regular  Babcock  test. 
The  reading  multiplied  by  two  gives  the  per  cent,  of 
fat  in  the  ice  cream.1 

»An  apparatus  for  determining  the  amount  of  overrun  (214)  in  the 
manufacture  of  ice  cream  has  been  devised  by  G.  H.  Benkendorf  of 
Wis.  exp.  station  (see  bull.  239  of  the  station). 


The  Lactometer  and  Its  Application.  101 

The  co-called  nitric-acid  test  of  ice  cream  is  made  as 
follows :  first,  prepare  a  mixture  of  12  cc.  concentrated 
nitric  acid  and  88  cc.  sulfuric  acid  (sp.  gr.,  1.82-1.83) ; 
second,  weigh  18  grams  of  the  sample  of  ice  cream  into 
a  beaker;  third,  add  about  9  cc.  of  this  acid  mixture 
to  the  ice  cream  in  the  beaker  and  mix  cautiously. 
When  the  foam  subsides,  notice  the  color  of  the  mix- 
ture ;  if  it  is  dark  brown,  no  more  acid  is  needed,  but  if 
the  ice  cream  is  not  at  all  dissolved,  add  more  of  the 
acid  mixture  until  a  clear,  chocolate-colored  liquid  is 
obtained.  The  contents  of  the  beaker  may  then  be 
rinsed  into  a  cream-test  bottle,  using  a  little  hot  water 
to  clean  out  the  beaker.  The  test  bottle  is  then  placed 
in  a  centrifuge  and  the  test  completed  in  the  usual  way.1 


Questions. 

1.  Why  is  it  difficult  to  get  accurate  tests  of  skim  milk  by 
the  Babcock  testf 

2.  Mention   at   least   three  precautions  that   should  be   taken 
in   testing  skim   milk. 

3.  Should   more   acid   be   used    for   full   milk    than    for   skim 
milk,  or  more  for  skim  milk  than  for  whey?     Why? 

4.  How  much   fat  is  probably  present   in   a  sample  of   skim 
milk  which  shows  no  fat  on  being  tested  in  a  skim  milk  bottle  t 

5.  What   per   cent,    of    fat   does   each    division   of   a    double- 
necked  skimmilk  test  bottle  represent? 

6.  How    can     (a)     butter,     (b)     cheese,    (c)     unsweetened    and 
sweetened  condensed  milk  be  tested  with  the  Babcock  testf 

7.  If  8.4  gr.  cheese  give  a  reading  of  12.2%  on  the  neck  of  a 
test  bottle,  what  per  cent,  of  fat  does  the  cheese  contain? 

8.  What  is  the   per  cent,   of   fat  in   a  sample  of  cheese,  of 
which  4.2  grams  contained   enough   fat  to   fill  the  space   in   the 
neck  of  a  Babcock  milk  test  bottle  from  1.7  to  9.5  mark? 

9.  How  can  the  per  cent,  of  fat  in  ice  cream  be  determined? 

'Wisconsin  exp.  station  bull.  262. 


CHAPTER  VI. 
THE    LACTOMETER    AND     ITS    APPLICATION. 

109.  The  lactometer  is  used  for  determining  the  spe- 
cific gravity  of  milk..  The  term  specific  gravity  means 
the  weight  of  a  certain  volume  of  a  solid  or  a  liquid 
substance  compared  with  the  weight  of  the  same  vol- 
ume of  water  at  4°  C.  (39.2°  Fahr.)  ;  for  gases  the 
standard  of  comparison  is  air  or  hydrogen.  If  the  milk 
which  a  can  will  hold  weighs  exactly  103.2  lt>s.,  this  can 
will  hold  a  smaller  weight  of  water,  say  100  Ibs.,  as  milk 
is  heavier  than  water;  the  specific  gravity  of  this  milk 

will  then  be  ~  =1.032. 

The  specific  gravity  of  normal  cow's  milk  will  vary 
in  different  samples  between  1.029  and  1.035  at  60°  F., 
the  average  being  about  1.032.  The  specific  gravity  of 
skim  milk  is  about  1.036-1.038,  and  of  sweet  cream  1.01 
to  .95,  according  to  the  per  cent,  of  fat  contained  there- 
in; average  specific  gravity  1.0  (see  p.  77). * 

The  lactometer  enables  us  to  determine  rapidly  the 
relative  weight  of  milk  and  water.  Its  application  rests 
on  well-known  laws  of  physics :  When  a  body  floats  in 
a  liquid,  the  weight  of  the  amount  of  liquid  which  it 
replaces  is  equal  to  the  weight  of  the  body.  It  will  sink 
further  into  a  light  liquid  than  into  a  heavy  one,  be- 

1  Since  a  gallon  of  water  weighs  8.34  IDS.,  1  gal.  of  milk  will  weigh 
s.34Xl-°32  or  8.6  Ibs. :  1  gal.  of  skim  milk,  8.7  IDS.,  and  1  gal.  of 
cream  from  8.1  to  8.5  Ibs.,  according  to  its  richness.  (See  Table  XVI, 
Appendix.) 


The  Lactometer  and  Its  Application. 


103 


cause  a  larger  volume  of  the  former  will 
be  required  to  equal  the  weight  of  the 
body.  A  lactometer  will  therefore  sink 
deeper  into  milk  of  a  low  specific  grav- 
ity than  into  milk  of  a  high  specific 
gravity. 

no.  The  Quevenne  lactometer.  - 
This  instrument  (fig.  39),  consists  of 
a  hollow  cylinder  weighted  by  means  of 
mercury  or  fine  shot  so  that  it  will  float 
in  milk  in  an  upright  position,  and  pro^ 
vided  with  a  narrow  stem  at  its  upper 
end,  inside  of  which  is  found  a  gradu- 
ated paper  scale.  In  the  better  forms, 
like  the  Quevenne  lactometer  shown  in 
the  figure,  a  thermometer  is  melted  into 
the  cylinder,  with  its  bulb  at  the  lower 
end  of  the  lactometer  and  its  stem  ris- 
ing above  the  lactometer  scale. 

The  scale  of  the  Quevenne  lactometer 
is  marked  at  15  and  40,  and  divided  into 
25  equal  parts,  with  figures  at  each  five 
divisions  of  the  scale.  The  single  divis- 
ions are  called  degrees.  The  15-degree 
mark  is  placed  at  the  point  to  which  the 
lactometer  will  sink  when  lowered  into 
a  liquid  of  a  specific  gravity  of  1.015, 
and  the  40-degree  mark  at  the  point  to 
which  it  will  sink  when  placed  in  a 
liquid  of  a  specific  gravity  of  1.040. 


FIG. 


104  Testing  Milk  and  Its  Products. 

The  specific  gravity  is  changed  to  lactometer  degrees 
by  multiplying  by  1000  and  subtracting  1000  from  the 
product. 

EXAMPLE:  Given,  the  specific  gravity  of  a  sample  of  milk, 
1.0345;  corresponding  lactometer  degree,  1.0345X1000—1000= 
34.5. 

Conversely,  if  the  lactometer  degree  is  known,  the 
corresponding  specific  gravity  is  found  by  dividing  by 
1000  and  adding  1  to  the  quotient  (34.5-f-1000=.0345 ; 
.0345+1=1.0345). 

in.  Influence  of  temperature.  Like  most  liquids, 
milk  will  expand  on  being  warmed,  and  the  same  vol- 
ume will,  therefore,  weigh  less  when  warm  than  before ; 
that  is,  its  specific  gravity  will  be  decreased.  It  follows 
then  that  a  lactometer  is  only  correct  for  the  tempera- 
ture at  which  it  is  standardized.  If  a  lactometer  sinks 
to  the  32-mark  in  a  sample  of  milk  of  a  temperature  of 
60°  F.,  it  will  only  sink  to,  say  33,  if  the  temperature 
of  the  milk  is  50°  F.,  and  will  sink  farther  down,  e.  g., 
to  31,  if  the  temperature  is  70°  F.  Lactometers  are 
generally  standardized  at  60°  F.,  and  to  show  the  cor 
rect  specific  gravity  the  milk  to  be  tested  should  first  be 
warmed  (or  cooled,  as  the  case  may  be)  to  exactly 
60°  F. 

112.  Correction  tables.  Tables  have  been  constructed 
for  correcting  errors  in  lactometer  readings  due  to 
differences  in  temperature.  As  the  fat  content  of  a 
sample  of  milk  has  a  marked  influence  on  its  specific 
gravity  at  different  temperatures,  the  co-efficient  of 
expansion  of  fat  differing  greatly  from  that  of  the 
milk  serum,  the  table  cannot  give  absolutely  accurate 


The  Lactometer  and  Its  Application.  105 

corrections  for  all  kinds  of  milk,  whether  rich  or  poor. 
But  the  error  introduced  by  the  use  of  one  table  for  all 
kinds  of  whole  milk  within  a  comparatively  small 
range  of  temperature,  like  ten  degrees  above  or  below 
60°,  is  too  small  to  have  any  importance  outside  of 
exact  scientific  work,  and  in  such,  the  specific  gravity 
is  always  determined  by  means  of  a  picnometer  or  a 
specific-gravity  bottle  (248),  at  the  exact  temperature 
at  which  this  has  been  calibrated.  ~In  taking  the  spe- 
cific gravity  of  a  sample  of  milk  by  means  of  a  lacto- 
meter, the  milk  is  warmed  or  cooled,  if  need  be,  so  that 
its  temperature  does  not  vary  ten  degrees  either  way 
from  60  degrees  P, 

113.  The  temperature  correction  table  for  whole  milk, 
given  in  the  Appendix  shows  that  if,  e.  g.,  the  specific 
gravity  of  a  sample  of  milk  taken  at  68°  P.  was  found 
to  be  1.034,  its  specific  gravity  would  be  1.0352  if  the 
milk  was  cooled  down  to  60°.  If  the  specific  gravity 
given  was  found  at  a  temperature  of  51°,  the  corrected 
specific  gravity  of  the  milk  would  be  1.0329. 

In  practical  work  in  factories  or  at  the  farm,  suffi- 
ciently accurate  temperature  corrections  may  generally 
be  made  by  adding  .1  to  the  lactometer  reading  for 
each  degree  above  60°  P.,  and  subtracting  .1  for  each 
degree  below  60°;  e.  g.,  if  the  reading  at  64°  is  32.5 
it  will  be  about  32.5+.4=32.9  at  60°  P.;  and  34.0  at 
52°  P.  will  be  about  34.0— .8=33.2  at  60°  P.  The  table 
in  the  Appendix  gives  33.0  as  the  corrected  figure  in 
both  cases. 

The  scale  of  the  thermometer  in  the  lactometer  should 
be  placed  above  the  lactometer  scale  so  that  the  tern- 


106  Testing  Milk  and  Its  Products. 

perature  may  be  read  without  taking  the  lactometer  out 
of  the  milk ;  this  will  give  more  correct  results  and  will 
facilitate  the  reading. 

114.  N.  Y.  Board  of  Health  lactometer.       In  the  East  and 
among  city    milk   inspectors   generally,    the    so-called   New   York 
Board  of  Health  lactometer  is  often  used.     This  does  not  give 
the  specific  gravity  of  the  milk  directly,  as  is  the  case  with  the 
Quevenne  lactometer;    but   the   scale    is   divided   into    120    equal 
parts,  known  as  Board  of  Health  degrees,  the  mark  100  being 
placed  at  the  point  to  which  the  lactometer  sinks  when  lowered 
into  milk  of  a  specific  gravity  of  1.029  (at  60°  F.) ;  this  is  con- 
sidered the  lowest  limit  for  the  specific  gravity  of  normal  cow's 
milk.     The  zero  mark  on  the  scale  shows  the  point  to  which  the 
lactometer  will  sink  in  water;    the   distance   between  these   two 
marks  is  divided  into  100  equal  parts,  and  the  scale  is  contin- 
ued below  the  100  mark  to  120.    As  100°  on  the  Board  of  Health 
lactometer   corresponds  to   29°   on   the  Quevenne  lactometer,   the 
zero  mark  showing  in   either   case   a  specific  gravity   of   1,  the 
degrees   on   the  former  lactometer    may   easily  be   changed    into 
Quevenne    lactometer   degrees   by    multiplying   by    .29.     To    fur- 
ther aid  in  this  transposition,  Table  III  is  given  in  the  Appen- 
dix, showing  the  readings  of  the   two   scales  between   60°   and 
120°  -on  the  Board  of  Health  lactometer. 

The  temperature  correction  for  Board  of  Health  lactometers 
is  as  follows:  for  each  degree  of  temperature  above  60°  F.  .3  is 
added  to  the  reading,  and  for  each  degree  below,  .3  is  subtracted.* 

115.  Reading  the  lactometer.    For  determining  the 
specific  gravity  of  milk  in  factories  or  private  dairies,  tin 
or  copper  cylinders  are  recommended,  l1/^  inches  in 
diameter  and  10  inches  high,  with  a  base  about  four 
inches  in  diameter  (see  fig.  39) ;  another  form  of  speci- 
fic-gravity cylinders,  in  use  in  chemical  laboratories,  is 
shown  in  fig.  40.    The  cylinder  is  filled  with  milk  of  a 
temperature  ranging  between  50°  and  70°  F.,  to  within 

1  A  special  form  of  lactometer  that  will  allow  of  very  accurate  read- 
ings has  been  constructed  by  Poetschke  (see  Jr.  Ind.  and  Eng.  Chem., 
1911.  p.  40fi). 


The  Lactometer  and  Its  Application.          107 

an  inch  of  the  top,  and  the  lactometer  is  slowly  lowered 
therein  until  it  floats;  it  is  left  in  the  milk  for  about 
half  a  minute  before  lactometer  and  thermometer  read- 
ings are  taken,  both  to  allow  the  escape  of  air  which 
has  been  mixed  with  the  milk  in  pouring  it,  prepara- 
tory to  the  specific-gravity  determination,  and  to  allow 
the  thermometer  to  adjust  itself  to  the  tem- 
perature of  the  milk.  The  lactometer  should 
not  be  left  in  the  milk  more  than  a  minute 
before  the  reading  is  taken,  as  cream  will  soon 
begin  to  rise  on  the  milk,  and  the  reading, 
if  taken  later,  will  be  too  high,  as  the  bulb 
of  the  lactometer  will  then  be  floating  in  par- 
tially skimmed  milk  (24).  In  reading  the  lac- 
tometer degree,  the  mark  on  the  scale  plainly 
visible  through  the  upper  portion  of  the 
meniscus  of  the  milk  should  be  noted.  Ow- 
ing to  surface  tension  the  milk  in  immediate 

r  IG.  4U.  Hp6- 

contact  with  the  lactometer  stem   will  rise  erne-gravity 

cylinder. 

above  the  level  of  the  surface  in  the  cylinder, 
and  this  must  be  taken  into  consideration  in  making  the 
readings.     It  is  not  necessary  to  read  closer  than  one- 
half  of  a  lactometer  degree  in  factory  or  dairy  work. 

116.  Time  of  taking  lactometer  readings.  The  spe- 
cific gravity  of  milk  should  not  be  determined  until  an 
hour  or  two  after  the  milk  has  been  drawn  from  the 
udder,  as  too  low  results  are  otherwise  obtained  (Beck- 
nagel's  phenomenon}.*  The  cause  of  this  phenomenon 
is  not  definitely  understood;  it  may  come  from  the  es- 
cape of  gases  in  the  milk,  or  from  changes  occurring  in 

» Milchztg.  1883,  419 ;  bull.  43,  Chem.  Div.,  U.  S.  Dept.  of  Agriculture, 
p.  191 ;  Analyst,  1894,  p.  76.  See  also  Flelgcbmann  and  Wlegner,  Jr 
f.  T,dw..  1913,  pp.  283-828. 


108  Testing  Milk  and  Its  Products. 

the  mechanical  condition  of  the  nitrogenous  compo- 
nents of  the  milk.  The  results  obtained  after  a  couple 
of  hours  will,  as  a  rule,  come  about  one  degree  higher 
than  when  the  milk  is  cooled  down  directly  after  milk- 
ing and  its  specific  gravity  then  determined. 

117.  Influence  of   solid  preservatives  on   lactome- 
ter readings.     When  potassium  bi-chromate,  corrosive 
sublimate,  etc.,  is  added  to  milk  samples  to  preserve 
them  from  souring   (190),  the  specific  gravity  of  the 
milk  will  be  increased;  with  the  quantity  usually  added 
(y2  gram  to  a  pint  of  milk)   the  increase  amounts  to 
about  1  lactometer  degree,  and  this  correction  of  lacto- 
meter readings  should  be  made  with  milk  samples  pre- 
served in  this  manner.     To  avoid  this  error,  Dr.  Eich- 
loff1  recommends  the  use  of  a  solution  of  potassium  bi- 
chromate in  water   (43  grams  to  1  liter),  the  specific 
gravity  of  which  is  1.032,  or  similar  to  that  of  average 
milk;  5  cc.  of  this  solution  is  required  for  a  pint  of 
milk.    No  correction  is  necessary  for  the  dilution  with 
this  small  amount  of  liquid  preservative,  or  when  a  few 
drops  of  formaldehyd  are  used  as  a  preservative. 

118.  Cleaning  the  lactometer.  The  lactometer  should 
be  cleaned  directly  after  using,  by  rinsing  with  cold 
water;  it  is  then  wiped  dry  with  a  clean  cloth  and 
placed  in  the  case. 

n8a.  Testing  the  accuracy  of  lactometers.  The 
correctness  of  lactometers  may  be  determined  with  a 
fair  degree  of  accuracy  by  placing  them  in  different 
salt  solutions  prepared  by  dissolving  exactly  3,  4,  and  5 
grams  of  pure  dairy  salt  in  100  grams  (cc.)  of  water. 
The  specific  gravities  at  60°  P.  of  solutions  thus  ob- 

'Technlk   dor   Milchfriifung,    p.   98. 


The  Lactometer  and  Its  Application.  109 

tained  are  1.022,  1.029,  and  1.036,  for  3,  4,  and  5  per 
cent,  solutions,  respectively. 

CALCULATION  OF  MILK  SOLIDS. 

119.  A  number  of  chemists  have  prepared  formulas 
for  the  calculation  of  milk  solids  when  the  fat  content 
and  the  specific  gravity  (lactometer  reading)  of  the 
milk  are  known.  By  careful  work  with  milk  tester  and 
lactometer  it  is  possible  by  means  of  these  formulas  to 
determine  the  composition  of  samples  of  milk  with  con- 
siderable accuracy,  both  cutside  of  and  in  chemical  lab- 
oratories. As  the  complete  formulas  given  by  various 
chemists  (Behrend  and  Morgen,  Clausnitzer  and  Mayer, 
Pleischmann,  Hehner  and  Eichmond,  Richmond,  Bab- 
eock)1  are  very  involved,  and  require  rather  lengthy 
calculations,  tables  facilitating  the  figuring  have  been 
prepared.  The  formulas  in  rise  at  the  present  time,  in 
this  country  and  abroad,  are  those  proposed  by  Pleisch- 
mann, Hehner  and  Richmond,  or  Babcock.  Babcock's 
formula  is  the  one  generally  taught  in  American  dairy 
schools  and  is  therefore  given  here  ;  it  forms  the  foun- 
dation for  Table  VI  in  the  Appendix  for  the  calculation 
of  solids  not  fat. 

By  the  use  of  these  tables  the  percents  of  solids  not 
fat  may  be  found,  corresponding  to  lactometer  read- 
ings from  26  to  36,  and  to  fat  contents  from  0  to  6 
per  cent.  The  formula,  as  amended  in  1895,2  is  as  fol- 
lows, S  being  the  specific  gravity  and  /  the  per  cent,  of 
fat  in  the  milk. 


Solids  not  fats  =  -l(100-f)2.5 


Agricultural  Science,  vol.  Ill,  p.  139. 

Wisconsin    rxporimont   station,   twolfth    roport.   page   120. 


110  Testing  Milk  and  Its  Products. 

The  derivation  of  this  formula  is  explained  in  the  re- 
port referred  to. 

120.  Short  formulas.  The  tables  made  up  from  this 
formula,  giving  the  percentages  of  solids  not  fat  corre- 
sponding to  certain  per  cents,  of  fat  and  lactometer 
readings,  are  given  in  the  Appendix.  A  careful  exam- 
ination of  the  tables  will  disclose  the  fact  that  the  per 
cent,  of  solids  not  fat  increases  uniformly  at  the  rate 
of  .25,  or  one-fourth  of  a  per  cent,  for  each  lactometer 
degree,  and  .02  per  cent,  for  each  tenth  of  a  per  cent,  of 
fat.  This  relation  is  expressed  by  the  following  simple 
formulas : 

Solids  not  f  at=J4  L -f  .2  f 
Total  solids=:%  L  +  1.2  f , 

L    being    the    lactometer    reading    at    60°    P.    (specific    gravity 
X  1000  —  1000),  and  /  the  per  cent,  of  fat  in  the  milk. 

Rule:  a,  To  find  the  per  cent,  of  solids  not  fat  in  milk,  add 
two-tenths  of  the  per  cent,  of  fat  to  one-fourth  of  the  lacto- 
meter reading,  and 

b,  To  find  the  per  cent,  of  total  solids  in  milk,  add  one  and 
two-tenths  times  the  per  cent,  of  fat  to  one-fourth  of  the  lacto- 
meter reading. 

These  formulas  and  rules  are  easily  remembered  and 
can  be  quickly  applied  without  the  use  of  tables.  The 
results  obtained  by  using  them  do  not  differ  more  than 
.04  per  cent,  from  those  of  the  complete  formula  for 
milks  containing  up  to  6  per  cent,  of  fat,  and  may  be 
safely  applied  in  practical  work. 

The  English  dairy  chemist  Droop  Richmond  has 
constructed  an  ingenious  sliding  "milk  scale"  which  en- 
ables one  to  readily  find  the  percentages  of  total  solids 


The  Lactometer  and  Its  Application.          Ill 

corresponding  to  different  lactometer  readings  and  fat 
contents,  or  the  percentage  of  fat  from  total  solids  and 
lactometer  readings.1 

ADULTERATION  OF  MILK. 

121.  Methods  of  adulteration.  The  problem  of  de- 
termining whether  or  not  a  sample  of  milk  is  adulter- 
ated becomes  an  important  one  in  the  work  of  milk  in- 
spectors and  food  chemists.  Managers  of  creameries 
and  cheese  factories  are  also  sometimes  interested  in 
ascertaining  possible  adulterations  in  the  case  of  some 
patron's  milk,  although  since  the  general  introduction  of 
the  Babcock  test  in  factories  and  the  payment  for  the 
milk  on  the  basis  of  the  amount  of  butter  fat  delivered, 
the  temptation  to  water  or  skim  the  milk  has  been 
largely  removed.  In  the  city  milk  trade,  especially  in 
our  larger  cities,  wateied  or  skimmed  milk  is  occasion- 
ally met  with,  in  spite  of  the  vigilance  of  their  milk  in- 
spectors or  the  officers  of  the  city  boards  of  health. 

When  the  origin  of  a  suspected  sample  of  milk  is 
known,  a  second  sample  should  always  be  taken  on  the 
premises,  if  possible,  by  or  in  the  presence  of  the  in- 
spector, and  the  composition  of  the  two  samples  com- 
pared. If  the  suspected  sample  is  considerably  lower 
in  fat  content  than  the  second,  so-called  control-sample, 
and  has  a  normal  or  high  per  cent,  of  solids  not  fat,  it  is 
skimmed;  if  the  fat  and  solids  not  fat  are  below  nor- 
mal, it  is  watered;  and  if  both  these  percentages  are 
abnormally  IOAV,  the  sample  is  most  likely  both  watered 
and  skimmed  (126). 

]  Dairy  Chemistry,  p.  69   (second  ed.) 


112  Testing  Milk  and  Its  Products. 

122.  Latitude  of  variation.     In  order  to  determine 
whether  or  not  a  sample  of  milk  is  skimmed  or  watered, 
or  both  skimmed  and  watered,  the  per  cents,  of  fat  and 
of  solids  not  fat  in  the  sample  must  be  ascertained,  and 
if  a  control-sample  can   be  secured,  these  determina- 
tions for  both  samples  compared.     The  proper  latitude 
to  be  allowed  for  the  natural  variation  in  the  composi- 
tion of  milk  differs  according  to  the  origin  of  the  milk ; 
in  case  of  milk  from  single  cows,  the  variations  in  fat 
content  from  day  to  day  may  exceed  one  per  cent.,  al- 
though under  ordinary  conditions  the  per  cent,  of  fat 
in  most  cow's  milk  will  not  vary  that  much.     The  con- 
tent of  solids  not  fat  is  more  constant,  and  rarely  va- 
ries one-half  of  one  per  cent,   from  day  to  day  with 
single  cows.  Cows  in  heat  or  sick  cows  may  give  milk  dif- 
fering considerably  in  composition  from  normal  milk.1 

123.  Mixed  herd  milk  is  of  comparatively  uniform 
composition  on  consecutive  days,  and  as  most  milk  of- 
fered for  sale  or  delivered  to  factories  is  of  this  kind, 
the  task   of  the  milk   inspector  is  made   considerably 
easier  and  more  certain  on  this  account.    Daily  varia- 
tions in  herd  milk  beyond  one  per  cent,  of  fat  and  one- 
half  per  cent,  of  solids  not  fat,  are  suspicious  and  may 
be  taken  as  fairly  conclusive  evidence  of  adulteration. 
This  is  especially  true  in  case  the  control-sample  shows  a 
comparatively  low  content  of  fat  or  solids  not  fat  (159). 

124.  Legal  standards.     Where  a  control-sample  can- 
not be  taken,  the  legal  standards  of  the  various  states 
for  fat  or  solids  in  milk  are  used  as  a  basis  for  calculat- 

»Blythe,   Foods,   their   Composition   and   Analysis,    London,    1903    p. 
250  et  seq. 


The  Lactometer  and  Its  Application.          113 

ing  the  extent  of  adulteration  of  a  sample  of  milk.  A 
list  of  legal  standards  for  milk  in  this  country  and 
abroad  is  given  in  the  Appendix.  These  standards  de- 
termine the  limits  below  which  the  milk  offered  for  sale 
within  the  respective  states  must  not  fall.  Legally  it 
matters  not  whether  a  sample  of  milk  offered  for  sale 
has  been  skimmed  or  watered  by  the  dealer  or  by  the 
cow ;  in  the  latter  case,  the  cows  producing  the  milk  are 
of  a  breed  or  a  strain  that  has  been  bred  persistently 
for  quantity  of  milk,  without  regard  to  its  quality.  In 
most  states  the  legal  standard  for  the  fat  content  of 
milk  is  3  per  cent.,  and  for  solids  not  fat  9  per  cent. 
There  are,  however,  cows  which  at  times  produce  milk 
containing  only  2.5  to  2.8  per  cent,  of  fat,  and  less  than 
8.5  per  cent,  solids  not  fat.  Such  milk  cannot  therefore 
be  legally  sold  in  most  states  in  the  Union,  and  the 
farmer  offering  such  milk  for  sale,  even  if  he  does  not 
know  the  composition  of  the  milk  produced  by  his  cows 
is  liable  to  prosecution  just  as  if  he  had  directly  watered 
the  milk.  By  mixing  the  milk  of  several  cows,  the 
chances  are  that  the  mixed  milk  will  contain  more  fat 
and  solids  not  fat  than  called  for  by  the  legal  standard ; 
if  such  should  not  be  the  case,  cows  producing  richer 
milk  must  be  added  to  the  herd  so  as  to  raise  the  qual- 
ity of  the  herd  milk  up  to  the  legal  standard,  or  the 
cows  giving  very  thin  milk  must  be  disposed  of. 

125.  The  specific  gravity  of  the  milk  solids.  A  calcula- 
tion of  the  specific  gravity  of  the  milk  solids  is  of  considerable 
assistance  in  interpreting  the  results  of  analyses  of  suspected 
milk  samples.  The  milk  solids  vary  but  slightly  in  specific 
gravity,  viz.,  between  1.25  and  1.34,  the  richer  milks  having  sol- 


114  Testing  Milk  and  Its  Products. 

ids  of  low  specific  gravities.     The  specific  gravity  of   the  milk 
solids  is  calculated  by  means  of  Fleischmann 's  formula 
t 


S  = 


100  s-100 
* 


s 

S  being  the  sp.  gr.  of  the  milk  solids,  a  that  of  the  milk  and  t 
the  total  solids  of  the  milk. 

Example:  A  sample  of  milk  has  been  found  to  contain  13.0 
per  cent,  of  solids,  sp.  gr.  1.032;  then  — ^!l^gz!?2_  =3.101; 

13.0-3.101=9.899;  ^^  =1.31,  the  specific  gravity  of  the  milk 
solids. 

The  specific  gravity  of  the  solids  does  not  change  if  the  milk 
is  watered,  while  it  is  increased  when  the  milk  is  skimmed.  If  a 
sample  of  milk  of  the  composition  given  in  the  preceding  ex- 
ample had  been  watered  so  as  to  reduce  the  solids  to  11.7  per 
cent  and  the  specific  gravity  to  1.0291  (as  would  be  the  case 
when  10  per  cent,  of  water  was  added),  we  would  again  have, 
by  calculation  as  above,  8=1.31.  If,  on  the  other  hand,  the 
milk  was  skimmed  so  as  to  reduce  the  solids  to  11.7  per  cent., 
thereby  increasing  the  specific  gravity  of  the  milk  to,  say  1.035, 
we  would  have  by  substituting  these  values  in  the  preceding 
formula,  3=1.41,  showing  conclusively  that  the  milk  had  been 
skimmed. 

An  addition  of  skim  milk  to  whole  milk  would  have  the.  same 
effect  as  skimming,  as  regards  the  composition  of  the  latter,  and 
the  specific  gravity  of  its  solids. 

The  specific  gravity  of  pure  butter  fat  at  60°  F.  is  .93,  and 
of  the  fat-free  milk  solids,  1.5847  (Fleischmann).  The  solids  of 
skim  milk  have  a  specific  gravity  of  1.56.  Samples  of  whole 
milk,  the  solids  of  which  have  a  specific  gravity  above  1.34  are 
suspicious,  and  a  specific  gravity  over  1.40  is  conclusive  evidence 
of  skimming. 

To  facilitate  the  calculation  of  the  specific  gravity  of  milk 
solids,  Table  IV  is  given  in  the  Appendix,  showing  at  a  glance 

the  value  of  -  -  for  specific  gravities  between  1.019  and 

1.0369.     An  example  will  readily  illustrate  the  use  of  the  table. 

Example:     A  sample  of  milk  has  a  specific  gravity  of  1.0343 

and  -.ontains  12.25  per  cent,  solids.     In  Table  IV,  we  find  in  the 


The  Lactometer  and  Its  Application.  115 

horizontal  line  beginning  with  1.034  under  the  column  headed 
0.00  13,  the  figure  3.316,  which  is  the  value  for  10°8~100  when 
s=]  0343.  Introducing  this  value  and  that  of  the  total  solids 
in  the  formula,  the  calculation  is  12.25 — 3.316=8.934;  12.25-f- 
8.934=1.37,  which  is  the  specific  gravity  of  the  solids  in  this 
case, 

726.  To  recapitulate.  Adulteration  of  milk  by  water- 
ing or  skimming,  or  both,  may  be  established  by  a  com- 
parison of  the  composition  of  the  suspected  sample  with 
that  of  a  control-sample,  or  if  none  such  can  be  ob- 
tained, with  the  legal  standards.  If  the  composition  of 
th(  two  samples  varies  appreciably,  the  milk  has  been 
adulterated,  and  the  character  of  the  adulteration  is 
shown  from  the  following  statement:  , 

If  the  analysis  of  the  suspected  sample 
Mows  the  milk  is 

sp.  gr.  of  milk i  \ 

fat  and  solids  not  fat \ l01  I        watered 

sp.    gr.   of   solids normal          j 

sp.  gr.  of  milk  and  of  solids__ -»  ,  .  ,  ) 

solids  not  fat—. } hlgil  \       skimmed 

fat    and   solids low  J 

sp.  gr.  of  milk normal  "j         watered 

sp.    gr.   of  solids normal  or  high    >  and 

fat  and  solids  not   fat._.  . low    -  j       skimmed 


The  extent  of  the  adulteration  is  determined  as  given 
below. 

127.  Calculation  of  extent  of  adulteration.1     In  the 

following  formulas,  percentages  found  iti  the  control- 
samples,  if  such  are  at  hand,  are  always  substituted  for 
the  legal  standards. 

a.  Skimming. — 1.  If  a  sample  of  milk  has  been 
skimmed,  the  following  formula  will  give  the  number 
of  pounds  of  fat  abstracted  from  100  Ibs.  of  milk : 

1  Woll,  Handbook  for  Farmers  and  Dairymen,  New  York,  1907,  pp. 
267-8. 


116  Testing  Milk  and  Its  Products. 

Fat  abstracted=legal  standard  for  fat — f,  .  .  (I) 
f  being  the  per  cent,  of  fat  in  the  suspected  sample. 

2.  The  following  formula  will  give  the  per  cent,  of 
fat  abstracted,  calculated  on  the  total  quantity  of  fat 
originally  found  in  the  milk: 

^y  ion 
r=10°-~iegal  standard  for  fat 

b.  Watering.— If  a  sample  is  watered,   the  calcula- 
tion is  most  conveniently  based  on  the  percentage  of 
solids  not  fat  in  the  milk.    The  percentage  adulteration 
may  be  expressed  either  on   basis  of  the  amount  of 
water  present  in  the  adulterated  milk,  or  the  amount  of 
water  added  to  the  original  milk : 

1.  Percent,  of  foreign  (extraneous]  water  in  the  adul- 
terated milk  =100-,—  3   S?i100  ,.  —(HI) 

legal  standard  for  solids  not  fat 

S  being  the  per  cent,  of  solids  not  fat  in  the  suspected 
sample. 

Example:  A.  sample  of  milk  contains  7.5  per  cent,  solids  not 
fat;  if  the  legal  standard  for  solids  not  fat  is  9  per  cent.,  then 

-^—g =16.7,  shows  the  per  cent,  of  extraneous  water 

in  the  milk. 

2.  Watering  of  milk  may  also  be  expressed  in  per 
cent,  of  water  added  to  the  original  milk,  by  formula  IV : 

Per  cent,  of  water  added  to  the  original  milk 

100  X  leg.   stand,   for  sol.  not  fat 

-g—  -100     (IV) 

In  the  example  given  above,1-^-9 — 100=20  per  cent 
of  water  was  added  to  the  original  milk. 

c.  Watering  and  skimming.— If  a   sample  has  been 
both  watered  and  skimmed,  the  extent  of  watering  is 


Babcock  Test  for  other  MUk  Products.  117 

ascertained  by  means  of  formula   (III)   or   (IV),  ana 
the   fat  abstracted   found   according   to   the   following 
formula : 
Per  cent,  fat  abstracted= 

3    £      f  A     leg-  stand,  for  sol.  not  fat 

leg.  stand,  for  fat  Xf .     .     (V) 

o 

Example:  A.  sample  of  milk  contains  2.4  per  cent,  of  fat  and 
8.1  per  cent,  solids  not  fat;  then 

Extraneous  water  in  milk=100-    JLl^M.  =10   per   cent. 

Fat  abstracted=3—  -^~-  =.33  per  cent,  or  11  per  cent  of 
total  fat  in  milk. 

100  Ibs.  of  the  milk  contained  10  Ibs.  of  extraneous  water  and 
.33  Ib.  of  fat  had  been  skimmed  from  it. 

For  methods  of  detection  of  other  adulterations  and 
of  preservatives  in  dairy  products,  see  Chap.  X,  299, 
et  seq. 

Questions. 

1.  What  is  the  weight  of  1000  cc.  of   (a)   water;    (b)    skim 
milk;    (c)    whole  milk;    (d)    cream  testing  30%  fat;    (e)   whey; 
(f)  butter  fat? 

2.  If  the  sp.  gr.   of  a  sample  of  milk   is  1.0325  at  68°   F., 
what  "is  the  lactometer  reading  at  60°? 

3.  What  effect  on   the  sp.   gr.  has   1.0%  solids   not  fat  and 
1.0%  fat? 

4.  How  can  the  accuracy  of  a  lactometer  be  determined? 

5.  If  a  sample  of  milk  has  a  sp.  gr.  of  1.032  and  13.0%  sol- 
ids, what  is   the  sp.  gr.  of   the  milk  solids? 

6.  How     can    (a)     skimmed     milk,    (b)     watered     milk,    (c) 
skimmed   and   watered  milk  be  detected? 

7.  Give   lactometer  readings  and  percentages  of  fat   in  sam- 
ples   showing    (a)    watering,    (b)    skimming,    (c)    watering    and 
skimming. 

8.  If  one  quart  of  water  is  added  to  one  quart  of  milk,  what 
per  cent,  of  water  is  added,  and  what  per  cent,  extraneous  water 
does   the  mixture   contain? 


118  Testing  Milk  and  Its  Products. 

9.  How  many  pounds  of  fat  have  been  removed  from  100 
pounds  of  a  sample  of  milk  testing  2.6%,  and  what  per  cent,  of 
the  fat  was  removed? 

10.  If  a  sample  of  milk  contains  7.0%  solids  not  fat,  what 
per  cent,  water  was  added  and  how  much  extraneous  water  did 
the  sample  contain? 

H.  What  has  probably  been  done  to  each  of  the  following, 
samples  of  milk,  that  were  found  to  contain  (a)  7.2  per  cent, 
solids  not  fat,  2.6  per  cent,  fat;  (b)  9.0  per  cent,  solids  not  fat, 
2.5  per  cent,  fat;  (c)  6.5  per  cent,  solids  not  fat,  2.4%  fat? 

12.  What  is  the  per  cent,  solids  not  fat  and  what  is  the  con 
dition  of  each  of  the  following  samples  of  milk: 

Lactometer  Beading.  Per  Cent  Fat. 

(a)  32.0  at  58°   P.  4.0 

(b)  33.5   at  56°   F.  2.5 

(c)  30.0   at  63°   F.  3.5 

(d)  28.0  at  54°   F.  2.5 

(e)  27.4  at  69°   F.  2.4 


CHAPTER  VII. 
TESTING  THE  ACIDITY  OF  MILK  AND  CREAM. 

128.  Cause  of  acidity  in  milk.     Even  directly  after 
milk  is  drawn  from  the  udder  it  will  be  found  to  have 
an  acid  reaction,  when  phenolphtalein  is  used  as  an  in- 
dicator.1    The  acidity  of  fresh  milk  is  not  due  to  the 
presence  of  free  organic  acids  in  the  milk,  like  lactic 
or  citric  acid,  but  to  acid  phosphates,  and  possibly  also 
in  part  to  free  carbonic  acid  gas  in  the  milk  or  to  the 
acid  reaction  of  casein.    Even  in  case  of  so-called  sweet 
milk,  the  amount  of  acidity  found  in  milk  fresh  from 
the    cow     or    nearly    so     is    on    the  average     about 
.07  per  cent.     When  the  milk  is  received  at  the  factory 
it  will  rarely  test  less  than  .10  per  cent,  of  acid,  calcu- 
lated as  lactid  acid;  some  patrons  bring  milk  day  after 
clay  that  does  not  test  over  .15  per  cent,  of  acid;  that 
of  others  tests  from  .20  to  .25  per  cent.,  and  some  lots, 
although  very  rarely,  will  test  as  high  as  .3  of  one  per 
cent,  of  acid.     It  has  been  found  that  milk  will  not 
usually  smell  or  taste  sour  or  ' '  turned, ' '  until  it  con- 
tains .30  to  .35  per  cent,  of  acid. 

129.  The  acidity  in  excess  of  that  found  normally  in 
milk  as  drawn  from  the  udder,  is  due  to  other  causes 
than  those  described.     Bacteriological  examinations  of 
milk  from  different  sources  and  of  milk  of  the  same 
origin  at  different  times  have  shown  that  there  is,  roughly 
speaking,  a  direct  relation  between  the  bacteria  found 

1  Freshly  drawn  milk  shows  an  amphoteric  reaction  to  litmus,  1.  e.. 
It  colors  blue  litmus  paper  red,  and  red  litmus  paper  faintly  blue. 


120  Testing  Milk  and  Its  Products. 

in  normal  milk,  and  its  acidity;  the  larger  the  number 
of  bacteria  per  unit  of  milk,  the  higher  is,  in  general, 
the  acidity  of  the  milk.  The  increase  in  the  acidity 
of  milk  on  standing  is  caused  by  the  breaking 
down  of  milk  sugar  into  lactic  acid  through  the  activi- 
ties of  acid-forming  bacteria.  Since  the  bacteria  get 
into  the  milk  through  a  lack  of  cleanliness  during  the 
milking,  or  careless  handling  of  the  milk  after  the 
milking,  or  both,  it  follows  that  an  acidity  test  of  new 
milk  will  give  a  good  clue  to  the  care  bestowed  in  hand- 
ling the  milk.  Such  tests  will  show  which  patrons  take 
good  care  of  their  milk  and  which  d6  not  wash  their 
cans  clean,  or  their  hands  and  the  udders  of  the  cows 
before  milking,  and  have,  in  general,  dirty  ways  in  milk- 
ing and  caring  for  the  milk.  The  acidity  test  is  always 
higher  in  summer  than  in  winter,  and  is  generally  high 
in  the  case  of  milk  kept  for  more  than  a  day  (Monday 
milk),  or  delivered  after  a  warm,  sultry  day  or  night. 
The  bacteria  have  had  a  good  chance  to  multiply  greatly 
in  such  milk,  even  if  it  be  kept  cooled  down  to 
40°-50°  P.,  and  as  a  result  considerable  quantities  of 
lactic  acid  have  been  formed.  The  determination  of  the 
acidity  of  fresh  milk  is  explained  in  detail  below  (147). 
130.  Method  of  testing  acidity.  Methods  of  meas- 
uring the  acidity  or  alkalinity  of  liquids  by  means  of 
certain  chemicals  giving  characteristic  color  reactions  in 
the  presence  of  acid  or  alkaline  solutions  (so-called 
volumetric  methods  of  analysis)  have  been  in  use  for 
many  years  in  chemical  laboratories.  They  were  applied 
to  milk  as  early  as  1872  by  Soxhlet,1  and  the  method 

1  Jour.  f.  prakt.  Chemle,  1872,  p.  6,  19. 


Testing  the  Acidity  of  Milk  and  Cream.        121 

worked  out  by  Soxhlot  an  dITenkel  has  since  been 
in  general  use  by  chemists.  They  measured  out 
50  cc.  of  milk  to  which  was  added  2  cc.  of  a  2  per  cent, 
alcoholic  solution  of  phenolphtalein,  and  this  was  ti- 
trated with  a  one-fourth  normal  soda  solution1  (see 
below).  In  this  country,  Dr.  A.  G.  Manns  in  1890  pub- 
lished the  results  of  work  done  in  the  line  of  testing 
the  acidity  of  milk  and  cream,2  and  the  method  of  pro- 
cedure and  apparatus  proposed  by  him  has  become 
known  under  the  name  of  Manns'  test,  and  is  being 
advertised  as  such  by  dealers  in  dairy  supplies. 

131.  Manns'  test.  The  acid  in  milk  or  cream  is 
measured  by  using  an  alkali  solution  of  a  certain  strength, 
with  an  indicator  which  shows  by  a  change  of  color  in 
the  milk  when  all  its  acid  has  been  neutralized.  Any  of 
the  alkalies,  soda,  potash,  ammonia,  or  lime  can  be  used 
for  making  the  standard  solution,  but  it  requires  the 
skill  and  apparatus  of  a  chemist  to  prepare  "it  of  the 
proper  strength.  A  tenth-normal  solution8  of  caustic 
soda  is  the  alkali  solution  used  most  frequently  in  de- 

1  Klrisohmiinn.    I.plirb.   d.   Milchwirtscbaft,  3rd   ed.,   p.  57. 

1  Illinois  experiment  station,  bulletin  9. 

s  Xormal  solutions,  as  a  general  rule,  are  prepared  so  that  one  liter 
shall  contain  the  hydrogen  equivalent  of  the  active  reagent  weighed 
in  grams  (Sutton).  Caustic  soda  (NaOlij  is  made  up  of  an  atom  each 
of  pndimu  (Xa),  oxygen  (O),  and  hydrogen  (II)  ;  its  molecular  weight 
is  therefore 

23+16+1=40 
NaOH 

A  normal  soda  solution  then  is  made  by  dissolving  40  grams  of  soda 
in  water,  making  up  the  volume  to  1000  cj. :  a  one-tenth  normal  solu- 
tion will  contain  one-tenth  of  this  amount  of  soda,  or  4  g~a~s  dissolved 
in  one  liter.  One  cubic  centimeter  of  the  latter  solution  will  contain 
.004  gram  of  soda,  and  will  neutralize  .009  gram  of  lactic  acid.  The 
formula  for  lactic  acid  is  CsHeOs  (see  p.  16),  and  its  molecular  weight 
is  therefore  3x12+6x1+3x16=90.  A  tenth-normal  solution  of  lactic 
acid  contains  9  grams  per  liter,  and  .009  gram  per  cubic  centimeter. 


122  Testing  Milk  and  Its  Products. 

termining  the  acidity  of  milk,  and  is  the  solution  labeled 
Neutralizer  of  the  Manns'  test. 

The  indicator  used  is  a  solution  of  phenolphtalein,  a 
light  yellowish  powder;  its  compounds  with  alkalies  are 
red,  in  weak  alkaline  solutions  pink  colored,  while  its 
acid  compounds  are  colorless.  The  phenolphtalein  solu- 
tion used  is  prepared  by  dissolving  10  grams  in  300  cc 
of  90  per  cent,  alcohol  (Mohr). 

132.  In  testing  the  acidity  of  either 
milk  or  cream  it  is  necessary  to  meas- 
ure out  with  exactness  the  quantity  of 
liquid    to    be    tested;    Manns    recom- 
mended using  a  50  cc.  pipette.     This 
amount  of  milk  or  cream  is  measured 
into  a  clean  tin,  porcelain  or  glass  cup, 
a  few  drops  of  the  phenolphtalein  so- 
lution   are    added,    and    the    Neutral- 
izer  (or  alkali  solution)   is  cautiously 
dropped  in  from  a  burette,  the  point  at 
which  the  solution  stands  before  any  is 
drawn  off  being  noted.     By  constant 
stirring  during  this  operation  it  will  be 
noticed  that  the  pink  color  formed  by 
the  addition  of  even  a  drop  of  alkali 
solution  will  at  first  entirely  disappear, 
but  as  more  and  more  of  the  acid  in 
the   sample   becomes  neutralized, 
the    color    will    disappear    more 
slowly,    until    finally    a    point    is 
reached  when  the  pink  color  re- 
Fl°'  Vn  MiSSS'Pat2t.n8ed  mains  Permanent  for  a  time.    No 


Testing   the  Acidity  of  Milk  and  Cream.        123 

more  alkali  should  be  added  after  the  first  appearance 
of  a  uniform  pink  color  in  the  sample.  This  color  will 
fade  and  gradually  disappear  again  on  standing,  owing 
to  the  effect  of  the  carbonic  acid  of  the  air,  to  which 
phenolphtalein  is  very  sensitive.  The  amount  of  the 
alkali  solution  used  for  the  test  is  then  obtained  from 
the  reading  on  the  scale  of  the  burette.  The  per  cent. 
of  acid  in  the  sample  is  calculated  by  multiplying  the 
number  of  cc.  of  alkali  solution  used,  by  .009  and  di- 
viding the  product  by  the  number  of  cc.  of  the  sample 
tested,  the  quotient  being  multiplied  by  100. 

c.  c    alkali X. 009 

Per  cent,  acidity— X100 

c.   c.  sample  tested 

If  50  cc.  of  cream  required  32  cc.  of  alkali  solution  to 
produce  a  permanent  pink  color,  the  per  cent,  of  acid  in 

the  cream  would   be  32x-009XlOO=.58  per    cent.     A 

/  oO 

part  of  this  calculation  may  be  saved  by  using  a  factor 

for  multiplying  the  number  of  cc.  of  alkali  added  in 
each  test.  This  factor  is  obtained  by  dividing  .009  (the 
number  of  grams  of  lactic  acid  neutralized  by  one  cc. 
of  alkali  solution)  by  the  number  of  cc.  of  sample 
tested,  and  multiplying  the  quotient  by  100.  If  a  50 
cc.  pipette  is  used  for  measuring  the  sample  to  be  tested, 
the  factor  will  be  (,009-f-50)  XlOO=.018;  if  a  25  cc. 
pipette  is  used,  the  factor  will  be  (. 009-^25  )X"100= 
.036:  and  if  a  20  cc.  pipette  is  used,  (. 009-=-20)  X 100= 
.045  will  be  the  factor  to  be  applied  in  calculating  the 
per  cent,  of  acidity,  the  number  of  cc.  of  alkali  used 
being  in  all  cases  multiplied  by  the  particular  factor 
corresponding  to  the  volume  of  the  sample  tested. 


124  Testing  Milk  and  Its  Products. 

133.  If  a  Babcock  milk  test  pipette  is  used  for  meas- 
uring the  milk  or  cream  to  be  tested  for  acidity,  the 
factor  will  be  (. 009-^17.6)  XlOO=.051.  This  is  so  nearly 
.05  that  sufficiently  accurate  results  may  be  obtained  by 
simply  dividing  the  number  of  cc.  used  by  two ;  the  re- 
sult will  be  the  tenths  of  per  cent,  of  acid  in  the  sample 
tested,  e.  g.,  if  17.6  cc.  of  cream  required  12  cc.  of  one- 
tenth  normal  alkali  to  give  a  pink  color,  then  the  per 
cent,  of  acid  is  12-^-2=.6  per  cent.     If  one-fifth  normal 
alkali   is  used   for  testing,  the   per  oont.   of  acidity  is 
shown  directly  by  the  number  of  cc.  used  (Vivian).1 

134.  Manns'  testing  outfit     The    apparatus    (see    fig.    41) 
and  chemicals  necessary  for  testing  the  acidity  of  milk  or  cream 
by  the  so-called  Manns'   test   include  one   gallon  of  a  one-tenth 
normal   alkali   solution;    four   ounces   of   an   alcoholic   solution   of 
phenolphtalein,    a   50    cc.    glass   burette    provided   with    a   pinch- 
cock,  a  burette  stand   and   a   pipette   for  measuring  the   sample. 
This  outfit  will  make  about  100  tests  and  is  sold  for  $5.00.* 

135.  The  alkaline  tablet  test.  Solid  alkaline  tab- 
lei  s  were  proposed  by  Farrington  in  1894,  as  a  substi- 
tute for  the  liquid  used  in  Manns'  test.3  It  was  found 
possible  to  mix  a  solid  alkali  carbonate  and  coloring 
matter,  and  compress  the -mixture  into  a  small  tablet, 
which  would  contain  an  exact  amount  of  alkali.  The 
advantage  of  the  tablets  lies  in  the  fact  that  they 

1  Van  Norman  recommends  the  use  of  a  50tb  normal  solution  for 
testing  cream  (see  Purdue  exp.  sta.,  bull  104).  37  cc.  01  a  normal  soda 
solution  is  diluted  to  1850  cc.  in  a  two-quart  bottle,  such  as  is  used  for 
mineral  waters.  Each  cc.  of  this  solution  represents  .01  cc.  of  acidity 
when  17.6  cc.  of  cream  is  measured  off.  The  titration  is  made  in  the 
usual  manner,  using  phenolphtalein  as  an  indicator.  See  also  Cornell 
Univ.  circ.  No.  7. 

*  Derarrta'*  nciilinieler  (Mik-hzeitung  180(5.  p.  7S5)  is  based  on  the 
same  principle  as  Manns'  tost:  one-tenth  soda  solution  is  added  to  100 
cc.  of  milk  in  a  glass-stoppered  granulated  flask.  ^  cc.  of  a  4  per  cent, 
phenolphtnlein  solution  being  used  as  an  indicator.  The  graduations 
on  the  neck  of  the  flask  give  the  "degrees  acidity"  directly. 

1  Illinois  oxperimcnt  station,  bulletin  3'J,  April.   1894. 


Testing  ike  Acidity  of  Milk  and  Cream.        125 


will  keep  far  better  than  a  standard  alkali  solution, 
and  they  can  be  safely  sent  by  mail ;  they  also  require 
less    apparatus    and    are    considerably    cheaper    than 
standard  alkali  solutions;  1000  of  these  tablets,  costing 
$2.00,    will   make   about   400    tests.1      Similar   alkaline 
tablets  were  placed  on  the  market  in  Europe  at  about 
the  same  time,  viz.,  Stokes'  Acidity    Pellets    in    1893. 
and    Eichler'sSaurepillen  (acid  pills)  in  1895.2 
Two  methods  of  using  the  tablets  have  been  proposed, 
one,  for  the  titration  (determination  of  acidity)  of  rip- 
ening cream  in  the  manufacture  of  sour-cream  butter; 
and  the  other,  for  determining  the  approximate  acidity 
of    different    lots    of    apparently 
sweet  milk  or  cream. 

136.  Determination  of  acidity 
in  sour  cream.  The  method  is 
equally  applicable  for  the  deter- 
mination of  the  acidity  of  sour 


Fio.  42.     Apparatus  used  for  determining  the  acidity  of  cream  or, milk. 

cream,  sour  milk  and  buttermilk,  but  is  most  frequently 
employed  in   testing  the  acidity  of  cream,   to  oxfimino 


The  tablets  are  sold  by  dealers  in  dairy 
Milchzeitung,  1895,  pp.  513-16. 


wpplit 


126  Testing  Milk  and  Its  Products. 

whether  or  not  the  ripening  process  has  reached  the 
proper  stage  for  churning  the  cream.  The  apparatus 
used  (see  fig.  42)  is  as  follows: 

1  17.6  cc.  pipette. 

1  white  cup. 

100  6c.  graduated  cylinders;  it  is  well  to  provide  two 
or  three  of  these,  although  only  one  is  strictly  necessary. 

137.  Preparation  of  the  solution.     The  tablet  solu- 
tion formerly  used  was  prepared  by  dissolving  five  tab- 
lets in  50  cc.  of  water;  with  20  cc.  of  cream  each  cubic 
centimeter  of  this  solution  represents  .017  per  cent,  of 
acid  (lactic  acid)  in  the  sample  tested.    The  amount  of 
acid  in  a  given  sample  is  then  obtained  by  multiplying 
the  number  of  cubic  centimeters  of  the  tablet  solution 
used,  by  .017. 

138.  According  to  a  suggestion  made  by  Mr.  C.  L. 
Fitch,1  the  strength  of  the  solution  was  changed  in  such 
a  manner  that  the  percentages  of  acidity  are  indicated 
directly  by  the  number  of  cubic  centimeters  of  tablet 
solution  used  in  each  test. 

The  17.6  cc.  pipette  may  be  used  for  measuring  the 
sample  for  acidity  testing,  and  the  results  read  directly 
from  the  graduated  cylinder,  if  the  tablet  solution  is 
prepared  by  taking  one  tablet  for  every  19.5  cc.  of 
water;  five  tablets  are  therefore  dissolved  in  97  cc.  of 
water. 

139.  As  cream  during  its  ripening  process  under  the 
conditions  present  in  this  country  generally  has  from 
.5  to  .6  per  cent,  of  acid  before  it  is  ready  to  be  churned, 


Hoard's  Dairyman,  Sept.  8,  1897. 


Testing  the  Acidity  of  Milk  and  Cream.        127 

a  50  cc.  cylinderful  of  tablet  solution  of  this  strength 
will  not  be  sufficient  to  make  a  test  of  cream  containing 
over  .5  per  cent,  of  acid,  although  it  is  enough  for  test- 
ing the  cream  up  to  this  point  during  the  ripening  pro- 
cess. The  acid-testing  outfit  should  therefore  contain  a 
100  cc.  graduated  cylinder,  instead  of  one  of  50  cc.  capa- 
city, so  that  cream  of  any  amount  of  acidity  up  to  1 
per  cent,  can  be  tested.  A  tablet  solution  of  the  strength 
given  has  not  only  the  advantage  over  the  solution  pre- 
viously recommended  (5  tablets  to  50  cc.  of  water)1 
of  showing  the  per  cent,  of  acidity  directly,  without 
tables  or  calculations,  but  being  weaker,  the  unavoid- 
able errors  of  determination  are  decreased  by  its  use. 

Since  a  17.6  cc.  pipette  is  found  in  creameries  and 
dairies  with  the  Babcock  test  outfit,  no  new  apparatus  is 
necessary  for  making  the  acidity  test  in  the  manner 
given. 

140.  The  preparation  of  the  standard  solution  is  as 
follows:  Five  tablets  are  placed  in  the  100  cc.  cylinder 
which  is  filled  to  the  97  cc.  mark  with  clean  soft  water.2 
The  cylinder  is  tightly  corked,  shaken  and  laid  on  its 
side,  as  the  tablets  dissolve  more  quickly  when  the  cyl- 
inder is  placed  in  this  position  than  when  left  upright 
with  the  tablets  at  the  bottom.  Several  cylinders  con- 
taining the  tablet  solution  may  be  prepared  at  a  time; 
as  soon  as  one  is  emptied,  tablets  and  water  are  again 
added,  and  the  cylinder  is  corked  and  placed  in  a  hori- 

*  Illinois  experiment  station,  bulletin  32 ;  Wisconsin  experiment  sta- 
tion, bulletin  52. 

*  Condensed  steam  or  rain  water  should  be  used,  and  not  hard  or 
alkali  water,  since  the  Impurities  In  these  affect  the  strength  of  the 
tablet  solution. 


128  Testing  Milk  and  Its  Products. 

zontal  position.  In  this  way  fresh  solutions  ready  for 
testing  are  always  at  hand.  The  cylinder  is  kept  tightly 
corked  while  the  tablets  are  dissolving,  so  that  none  of 
the  liquid  is  lost  by  the  shaking.  It  is  well  to  put  the 
tablets  in  the  cylinder  with  water  at  night;  the  solution 
will  then  be  ready  for  use  in  the  morning.  Excepting 
a  flocculent  residue  of  inert  matter,  "settlings,"  which 
will  -not  dissolve,  the  tablets  must  all  disappear  in  the 
solution  before  this  is  used.  The  strength  of  the  tablet 
solution  does  not  change  perceptibly  by  standing,  at 
least  for  one  week.  The  only  precaution  necessary  is 
to  avoid  evaporation  of  the  solution  by  keeping  the  cyl- 
inders tightly  corked.  The  solid  tablets  will  not  change 
if  kept  dry,  any  more  than  dry  salt  changes  by  age. 

141.  Accuracy  of  the  tablets.  The  tablets  have  been 
repeatedly  tested  by  chemists  and  found  to  be  accurate 
and  uniform  in  composition.  Tests  made  with  the 
tablets  according  to  the  directions  here  given  can  there- 
fore be  relied  on  as  correct.  The  alkali  solution  is  very 
sensitive,  however,  and  should  not  be  measured  in  a  cyl- 
inder which  has  been  previously  used  for  measuring 
sulfuric  acid,  as  the  smallest  drop  or  film  of  acid  from 
a  dish  or  from  the  operator's  fingers  will  change  the 
strength  of  the  standard  tablet  solution. 

1413.  Powdered  sodium  carbonate  weighed  out  in 
the  exact  quantity  required  for  making  a  gallon  of 
tenth  normal  solution  has  of  late  been  placed  on  the 
market;  these  "test  powders"  are  cheaper  than  alka- 
line tablets  and  when  put  out  by  a  reliable  firm  may 
be  depended  upon  to  be  accurate. 


Testing  the  Acidity  of  Milk  and  Cream.  129 

142.  Making  the  acidity  test.      The  cream  to  be 
tested  is  thoroughly  mixed,  and  17.6  cc.  are  measured 
into  the  cup.  The  pipette  is  rinsed  once  with  water,  and 
the  rinsings  added  to  the  cream  in  the  cup.  A  few  cc.  of 
the  tablet  solution  prepared  as  given  above  are  now 
poured  from  the  cylinder  into  the  cream  and  mixed 
thoroughly  with  it  by  giving  the  cup  a  gentle  rotary 
motion.    The  tablet  solution  is  added  in  small  quanti- 
ties until  a  permanent  pink  color  appears  in  the  sam- 
ple.   The  number  of  cc.  of  tablet  solution  which  has 
been  used  to  color  the  cream  is  now  read  off  on  the 
scale  of  the  cylinder. 

In  comparing  the  results  of  one  test  with  another, 
the  same  shade  of  color  should  always  be  adopted.1 
The  most  delicate  point  is  the  first  change  from  pure 
white  or  cream  color  to  a  uniform  pink  which  the  sam- 
ple shows  when  the  acid  contained  therein  has  beer 
neutralized.  This  shade  of  color  is  easily  recognized 
with  a  little  practice.  The  pink  color  is  not  permanent 
unless  a  large  excess  of  the  alkaline  solution  has  been 
added,  on  account  of  the  influence  of  the  carbonic  acid 
of  the  air  (132),  and  the  operator  should  not  therefore 
be  led  to  believe  by  the  reappearance  of  the  white  color 
after  a  time,  that  the  point  of 'neutralization  was  not 
already  reached  when  the  first  uniform  shade  of  pink 
was  observed. 

143.  Acidity  of  cream.     17.6  cc.  of  sweet  cream  is 

'A  helpful  suggestion  has  been  made  by  the  Danish  State  Dairy  In 
structor,  Dr.  G.  Ellbrecht,  for  obtaining  a  uniform  color  in  acidity  tests. 
Small  strips  of  pink  paper  are  moistened  and  attached  to  the  cup  or 
glass  in  which  the  titration  is  made,  and  alkali  solution  is  added, 
until  the  color  of  the  milk  or  cream  corresponds  to  that  of  the  strips. 

I 


130  Testing  Milk  and  Its  Products. 

generally  neutralized  by  15  to  20  cc.  of  this  tablet  solu- 
tion, representing  from  .15  to  .20  per  cent,  of  acid.  A 
mildly  sour  cream  is  colored  by  35  cc.  tablet  solution,  and 
a  sour  cream  ready  for  churning  by  about  50  to  60  cc. 
tablet  solution.  As  the  cream  ripens,  its  acidity  in- 
creases. The  rate  of  ripening  depends  largely  on  the  tem- 
perature at  which  the  cream  is  kept.  Cream  containing 
.5  to  .6  per  cent,  of  acid  will  make  such  butter  as  the 
general  American  market  demands  at  the  present  time 
Cream  showing  an  acid  test  of  .55  per  cent,  may  not  be 
too  sour,  but  .65  per  cent,  of  acid  is  very  near,  if  not 
on  the  danger  line,  since  such  cream  is  likely  to  make 
strong  flavored>  almost  rancid  butter  Bach  lot  of  cream 
should  be  tested  as  soon  as  it  is  ready  for  ripening,  and 
the  result  of  the  test  will  show  whether  the  cream  should 
be  warmed  or  cooled  in  order  to  have  it  ready  for  churn- 
ing at  the  time  desired.  Later  tests  will  show  the  rate 
at  which  the  ripening  is  progressing,  and  the  time  when 
the  cream  has  reached  the  proper  acidity  for  churning. 
144.  The  influence  of  the  richness  of  cream  on  the 
acid  test  has  been  studied  by  Professor  Spillman,1  and 
others.2  Since  the  acidity  develops  in  the  cream  serum, 
it  follows  that  an  acidity  of,  say  .5  per  cent,  in  a  40 
per  cent,  cream  represehts  a  larger  acidity  than  in  20 
per  cent,  of  cream,  e.  g. ;  in  the  former  case  we  have  .5 
gram  of  acid  in  60  grams  of  serum  (=.83  per  cent,  of 
the  serum) ;  in  the  latter  case  .5  gram  acid  is  found  in 
80  grams  serum  (=.63  per  cent,  of  the  serum) .  There- 

1  Washington  experiment  station,  bulletin  32. 

'Chicago  Dairy  I'rodm-e.  April  21,  1900,  p.  30 ;  Iowa  expt.  sta.,  buK 
52.   . 


Testing  the  Acidity  of  Milk  and  Cream.        131 

fore,  rich  cream  need  not  be  ripened  to  as  high  a  degree 
of  acidity  as  thin  cream.  A  table  is  given  in  the  Iowa 
bulletin  referred  to,  showing  the  relation  between  the 
richness  and  the  acidity  of  cream. 

145.  Spillman's  cylinder.  The  graduated  cylinder  shown  in 
fig.  43  was  devised  by  Professor  Spillman  for  use  in  testing  the 
acidity  of  milk  and  cream  with  Farrington's  alkaline  tablets. 
The  following  directions  are  given  for  making 
tests  with  this  piece  of  apparatus:1 

"All  that  is  needed  in  addition  to  the  acid-test 
graduate  shown  in  the  accompanying  illustration, 
is  a  common  prescription  bottle  of  six  or  eight 
ounce  capacity,  and  a  package  of  Farrington's 
alkaline  tablets.  Fill  the  bottle  with  water  and 
add  one  tablet  for  each  ounce  of  water  in  the 
bottle.  Shake  the  bottle  frequently  to  aid  in  dis- 
solving the  tablets. 

"Making  the  test.  In  making  the  test,  the 
acid-test  graduate  is  filled  to  the  zero  mark  with 
the  milk  or  cream  to  be  tested.  The  tablet  solu- 
tion is  then  added;  a  little  at  a  time,  and  the 
graduate  shaken  after  each  addition,  in  order  to 
thoroughly  mix  the  milk  and  the  tablet  solution.  _: 
Tn  shaking  the  graduate,  give  it  a  rotary  motion  J?IQ.  43.  gpili- 
to  prevent  .spilling  any  of  the  liquid.  Continue  ™*°'B  lncyl!,°?|£ 
adding  the  tablet  solution  until  a  permanent  pink  mining  the  acid- 
color  can  be  detected  in  the  milk.  The  level  of  £y,kof  cream  or 
the  liquid  in  the  graduate,  measured  by  the  scale 
on  the  graduate,  will  then  show  the  per  cent,  of  the  acidity  of  the 
milk.  Tt  is  best  to  stand  the  graduate  on  a  piece  of  white  paper, 
so  that  the  first  pink  coloration  of  the  milk  may  be  easily  de- 
tected. ' ' 

146.  The  Marschall  acid  test  (see  fig.  44)  is  a  con- 
venient apparatus  for  determining  the  acidity  of  milk, 
cream,  or  whey.2  Tt  is  used  with  a  tenth-normn1  alkaline 


Washington  experiment  station,  bulletin   24. 
'  SPP  Wig.  exp.  sta..  bnll.  129. 


Testing  Milk  and  Its  Products. 


solution  ("Neutralize!-"),  9  cc.  of  milk,  cream,  etc., 
being  measured  out  for  the  test,  and  alkali  solution 
added  from  the  combined  burette  and  bottle,  the  former 
1  icing  graduated  to  two-tenths  cf  one  cc.  The  burette 
is  filled  by  tipping  tlie  bottle  and  the  surplus  of  the 
"neutrali/er"  will  flow  back,  leaving  the  solution  at 
the  zero  mark.  With 
the  quantity  of  milk 
given,  the  readings  ob- 
tained represent  per 
cent  of  acidity  direct. 
147.  Rapid  estima- 
tion of  the  acidity 
of  apparently  sweet 
milk  or  cream.  a, 
Milk.  The  alkaline 
tablet  method  offers  a 
ready  means  of  esti- 
mating the  acidity  of 
milk  or  cream  that  is 
still  sweet  to  the  taste. 
The  selection  of  the 
best  kinds  of  milk 
is  especially  important 
in  pasteurizing  milk 
or  cream.  As  previously  noted,  milk  which  gives  the 
highest  acid  test  contains,  as  a  rule,  a  larger  number  of 
bacteria  and  spores  not  destroyed  by  pasteurization 
than  does  milk  giving  a  low  acid  test  (129) ;  the  acidity 
test  may  therefore  be  used  to  advantage  for  the  pur- 
pose of  selecting  milk  best  adapted  for  pasteurization, 


FKJ.  44.     The  Marschnll  acid  test. 


Testing  the  Purity  of  Milk. 


133 


as  well  as  such  as  is  to  be  retailed  or  used  in  the  manu- 
facture of  high-grade  butter  and  cheese. 

In  distinguishing  milk  fit  for  pasteurization  purposes 
from  that  which  is  doubtful,  an  arbitrary  standard  of 
two-tenths  of  one  per  cent,  of  acid  may  be  taken  as  the 


&  Ounce  Bottle.  "Measure 


FIG.  45.     Apparatus  used  for  rapid  estimation  of  the  acidity  of  ap- 
parently sweet  milk  or  cream. 

upper  limit  for  milk  of  the  former  kind.  The  appara- 
tus used  in  making  this  test  is  shown  in  the  accompany- 
ing illustration  (fig.  45),  and  consists  of  a  white  tea- 
cup; a  four-,  six-,  or  eight-ounce  bottle,  and  a  No.  10 
brass  cartridge  shell,  or  a  similar  measure.  A  solution 
of  the  tablets  in  water  is  first  prepared,  one  tablet  being 
always  added  to  each  ounce  of  water:  four  tablets  in  a 
four-ounce  bottle;  six,  in  a  six-ounce  bottle,  etc.,  the 
amount  of  tablet  solution  prepared  depending  on  the 


134  Testing  Milk  and  Its  Products. 

number  of  tests  to  be  made  at  a  time.  The  bottle  is  filled 
up  to  its  neck  with  clean,  soft  water,  and  the  solution 
prepared  in  the  manner  previously  given  (140). 

148.  Operating  the  test.  As  each  lot  of  milk  is 
brought  to  the  creamery  in  the  morning  and  poured  into 
the  weigh  can,  a  cartridge-shell  dipper  is  filled  with 
milk  and  this  is  poured  into  the  white  cup.  The  same  or 
another  No.  10  shell  is  now  filled  twice  with  the  tab- 
let solution  and  emptied  into  the  milk  in  the  cup.  In- 
stead of  dipping  twice  with  one  measure  or  a  No.  10 
shell,  a  tin  measure  can  be  made  holding  as  much  as  two 
No.  10  shells,  or  the  tablet  solution  may  be  made  of 
double  strength;  that  is,  two  tablets  to  each  ounce  of 
water  and  the  same  sized  measure  used  for  both  the  milk 
and  the  tablet  solution.  The  liquids  are  then  mixed  in 
the  cup  by  giving  this  a  quick,  rotary  motion,  and  the 
color  of  the  mixture  noticed.  If  the  milk  remains  white 
it  contains  more  than  two-tenths  of  one  per  cent,  of  acid 
and  should  not  be  used  for  pasteurization.  If  it  is  col- 
ored after  having  been  thoroughly  mixed  with  two 
measures  of  tablet  solution,  it  contains  less  than  this 
amount  of  acid  and  may,  as  far  as  acidity  goes,  be  safely 
used  for  pasteurization  or  for  any  other  purpose  which 
requires  thoroughly  sweet  milk.  The  shade  of  color  ob- 
tained will  vary  with  different  lots  of  milk;  the  sweet- 
est milk  will  be  most  highly  colored,  but  a  milk  retain- 
ing even  a  faint  pink  color  with  two  measures  of  tablet 
solution,  or  one  measure  of  the  double  strength  solution 
to  one  measure  of  milk,  contains  less  than  .2  per  cent, 
of  acid. 


Testing  the  Acidity  of  Milk  and  Cream.  ^35 

By  proceeding  in  the  manner  described,  the  man  re- 
ceiving and  inspecting  the  milk  .at  the  weigh-can 
is  able  to  test  the  acidity  of  the  milk  delivered  nearly  as 
quickly  as  he  can  weigh  it;  and  according  to  the  results 
of  the  test  he  can  send  the  milk  to  the  general  delivery 
vat  or  to  the  pasteurization  vat,  as  the  weigh-can  may 
be  provided  with  two  conductor  spouts. 

149.  Size  of  measure  necessary.    It  is  not  necessary 
to  use  a  No.  10  shell  for  a  measure  in  working  the  pre- 
ceding method;  one  of  any  convenient  size  that  can  be 
filled  accurately  and  quickly,  will  answer  the  purpose 
equally  well,  if  a  measure  of  the  same  size  is  used  for 
both  the  sample  and  the  tablet  solution.    Each  measure 
ful  of  tablet  solution  made  up  as  directed,  will  in  this 
case  represent  one-tenth  per  cent,  of  acid  in  the  sam- 
ple tested.1 

150.  b,  Cream.     Cream  can  be  tested  in  the  way  al- 
ready described  for  testing  the  acidity  of  fresh  milk,  by 
adding  to  one  measureful  of  cream  in  the  cup  as  many 
measures  of  tablet  solution  as  are  necessary  to  change 
the  color  of  the  cream  when  the  two  liquids  are  thor 
oughly  mixed.    If  one  measure  of  tablet  solution  colors 
one  measure  of  cream,  this  contains  less  than  .1  per 
cent,  acid;  if  five  measures  of  tablet  solution  are  re- 
quired, the  cream  contains  about  .5  per  cent,  acid,  etc. 
By  proceeding  in  the  manner  described,  the  operator 
can  estimate  the  acidity  to  within  .05  per  cent,  of  acid, 
if  half  measures  of  tablet  solution  are  added.     The  re- 

1  In  European  creameries  and  city  milk  depots  the  alcohol  test  is 
often  applied  to  every  can  of  man  received ;  milk  that  is  sufficiently 
sour  to  be  noticed  by  the  taste,  will  coagulate  when  mixed  with  an  equal 
folume  of  70%  alcohol. 


136  Testing  Milk  and  Its  Products. 

suits  thus  obtained  are  sufficiently  delicate  for  all  prac- 
tical purposes. 

151.  Detection  of  boracic  acid  preservatives  in  milk.     The 

application  of  the  alkaline  tablet  test  for  detecting  the  boracic  acid 
in  milk  was  first  discussed  in  bulletin  No.  52  of  Wisconsin  experi- 
ment station.  The  acidity  of  the  milk  is  increased  by  the  addi- 
tion of  boracic  acid,  but  neither  the  odor  nor  the  taste  of  the 
milk  is  affected  thereby.  By  adding  to  sweet  milk  the  amount 
of  boracic  acid  which  will  keep  it  sweet  36  hours,  its  acidity  may 
be  increased  to  .35  per  cent.,  in  a  sample  of  milk  which  pre- 
viously tested  perhaps  only  .15  per  cent.  acid. 

As  before  stated,  unadulterated  milk  will  usually  smell  or 
taste  sour  or  ' '  turned, ' '  when  it  contains  .30  to  .35  per  cent,  acid 
(121);  milk  testing  as  high  as  this  limit,  which  neither  smells 
nor  tastes  sour  in  any  way,  is  therefore  in  all  probability  adul- 
terated with  some  preparation  containing  boracic  acid  or  a  simi- 
lar compound. 

152.  "Alkaline  tabs."        These  are  not  the  alkaline  tablets, 
but  a  substitute  which  was  put  on  the  market  by  a  New  York 
firm.     The  outfit  furnished  consisted  of  four  packages  of  paper 
discs  made  of  heavy  filter  paper,  each  of  about  the  size  of  an  old- 
style  copper  cent;  two  packages  of  square  paper;  one  glass  of  about 
10  cc.  capacity,  and  one  small  glass  bottle.     An  investigation  of 
these  "Tabs"  soon  disclosed  the  fact  that  they  were   entirely 
inaccurate,  and  that  no  dependence  could  therefore  be  placed  on 
the  results  obtained  by  their  use. 

Questions. 

1.  Tf  20  cc.  cream  require  12  cc.  —  alkali  for  neutralization, 
what  per  cent,  acid  in  the  sample  t 

2.  If  1   cc.  -^-  alkali  neutralize  .009  gram  lactic  acid,  what  is 

the  per  cent,  of  acid  in  a  sample  of  cream,  which  required  12  cc. 
alkali  for  25  cc.  of  cream  f 

3.  What   apparatus   and   strength   of   solution    must   be    taken 
to  show  per  cent,  acidity  directly  from  cc.  alkali  used  with  Far 
rington's  alkaline  tablets? 

4.  Tf  cream  testing  20%  fat  has  an  acidity  of  .6%,  what  will 
be  the  correppon'  u?  acidity  of  cream  testing  40%  fatt 


CHAPTER  VI11. 
TESTING  THE    PURITY  OF  MILK. 

153.  The  Wisconsin  curd  test.     Cheese  maken.  are 
often   troubled   with  so-called   floating   or  gassy   curds 
which  produce  cheese  defective  in  flavor  and  texture. 
These  faults  are  usually  caused  by  some  particular  lot 
of  milk  containing  impurities  that  cannot  be  detected 
by  ordinary  means  of  inspection.     The  Wisconsin  curd 
test  is  used  to  detect  the  source  of  these  defects  and 
thus  enable  the  cheese  maker  to  exclude  the  milk  from 
the  particular  farm   or   cow  to   which  the   trouble   is 
traced.     This  test  is  similar  in  principle  to  tests  that 
have  long  been  in  use   in   cheese-making   districts   in 
Europe,  notably  in  Switzerland,1  but  was  worked  out 
independently  at  the  Wisconsin  Dairy  School  in  1895 
and  is  now  generally  known  as  the  "Wisconsin  Curd 
Test."2 

154.  Method  of  making  the  test.     Pint  glass  jars, 
thoroughly  cleaned  and  sterilized  with  live  steam,  are 
provided;  they  are  plainly  numbered  or  tagged,  one 
jar  being  provided  for  each  lot  of  milk  to  be  tested.  The 
jars  are  filled  about  two-thirds  full  with  milk  from  the 
various  sources;  it  is  not  necessary  to  take  an  exact 

1  Herz,  Unters.  d.  Kuhmilch,  Berlin,  1889,  p.  87 ;  Slats,  Unters.  landw. 
wicht.  Stoffe,  1903,  p.  140. 

*  Wisconsin"  experiment  station,  twelfth  report,  p.  148.  The  appar- 
atus used  for  the  test  was  greatly  improved  in  1898,  and  a  description 
of  the  improved  test  is  given  in  bulletin  No.  67  and  the  annual  report 
of  the  Station  for  1898  (fifteenth  report,  pp.  47-53),  from  which  source 
the  accompanying  illustration  is  taken  (see  fig.  46). 


138 


Testing  Milk  and  Its  Products. 


quantity;  they  are  then  placed  in  a  water  tank,  the 
water  of  which  is  heated  until  the  milk  in  the  jars  has 
a  temperature  of  98°  P.  In  transferring  the  thermom- 
eter used  from  one  jar  to  another,  special  care  must  be 
taken  to  clean  it  each  time  in  order  to  prevent  contami- 
nation of  pure  lots  of  milk  by  impure  ones. 

When  the  milk  has  reached  a  temperature  of  98 °, 
add  to  each  sample  ten  drops  of  rennet  extract,  and  mix 
by  giving  the  jar  a  rotary  motion.  The  milk  is  thus 
curdled,  and  the  curd  allowed  to  stand  for  about  twenty 


PIG.  46.  Cross-section  of  the  Wisconsin  curd  test,  T.T-TJ",  testing 
jars  showing  different  stages  of  test ;  WL,  water  line ;  M,  milk  ;  F, 
frame ;  WS,  stand  to  support  cover ;  AI,  drain  holes ;  WO,  water  out- 
let;  DP,  drain  pall. 

minutes  until  it  is  firm.  It  is  then  cut  fine  with  a  case 
knife,  and  stirred  at  intervals  for  one-half  to  three- 
quarters  of  an  hour  sufficiently  to  keep  the  curd  from 
matting  under  the  whey.  When  the  cubes  are  quite  firm 
the  whey  is  poured  off  and  the  curd  left  to  mat  at  the 
bottom  of  the  bottles  if  the  old  form  of  apparatus  is 
used.  The  best  tests  are  made  when  the  separation  of 
the  whey  is  most  complete.  By  allowing  the  samples  to 
stand  for  a  short  time,  more  whey  can  be  poured  off, 
and  the  curd  thereby  rendered  firmer.  The  water  around 
the  jars  is  kept  at  a  temperature  of  98°,  the  vat  is  cov- 


Testing  tke  Purity  of  Milk.  139 

ered,  and  the  curds  allowed  to  ferment  in  the  sample 
jars  for  six  to  twelve  hours. 

During  this  time  the  impurities  in  any  particular 
sample  will  cause  gases  to  be  developed  in  the  curds  so 
that  by  examining  these,  by  smelling  of  them  and  cut- 
ting them  with  a  sharp  knife,  those  having  a  bad  flavor, 
or  a  spongy  or  in  any  way  abnormal  texture  may  be 
easily  detected,  and  thus  traced  to  the  milk  causing  the 
trouble. 

Since  the  curd  test  was  first  described,  several  modi- 
fications have  been  made  in  the  apparatus.  In  one  of 
these  the  bottles  are  held  in  a  covered  metal  frame  so 
that  all  of  them  can  be  drained  at  once  by  inverting  the 
frame. 

*55>  By  proceeding  in  the  way  described  with  the 
milk  from  the  different  cows  in  a  herd,  the  mixed  milk 
of  which  produced  abnormal  curds,  the  source  of  con- 
tamination in  the  herd  may  be  located.  Very  often  the 
trouble  will  be  found  to  come  from  the  cows  drinking 
foul  stagnant  water  or  from  fermenting  matter  in  the 
stable.  In  the  former  case  the  pond  or  marsh  must  be 
fenced  off,  or  the  cows  kept  away  from  it  in  other  ways ; 
in  the  latter,  a  thorough  cleaning  and  disinfection  of 
the  premises  are  required.  If  the  milk  of  a  single  cow 
is  the  source  of  contamination,  it  must  be  kept  by  itself, 
until  it  is  again  normal ;  under  such  conditions  the  milk 
.from  the  healthy  cows  may,  of  course,  safely  be  sent 
to  the  factory. 

156.  The  fermentation  test.  The  Gerber  fermentation 
test  (see  fig.  47)  also  furnishes  a  convenient  method  for 
examining  the  purity  of  different  lots  of  milk.  The  test  consists 
of  a  tin  tank  which  can  be  heated  by  means  of  a  small  lamp, 


140  Testing  Milk  and  Its  Products. 

and  into  which  a  rack  fits,  holding  a  certain  number  of  cylin- 
drical glass  tubes;  these  are  all 'numbered  and  provided  with  a 
mark  and  a  tin  cover. 
In  making  the  test,  the 
tubes  are  filled  to  the 
mark  with  milk,  the  num- 
ber of  each  tube  being 
recorded  in  a  note  book, 
opposite  the  name  of  the 
patron  whose  milk  was 
placed  therein.  The 
tubes  in  the  rack  are- 
put  in  the  tank,  which  is 

«  •   j     j-  11      *         x  Fi°     47>-     Thp   Orher  fermentation    test, 

two-thirds  full  of  water; 

the  temperature  of  the  water  is  kept  at  104-106°  P.,  for 
six  hours,  when  the  rack  is  taken  out,  the  tubes  gently  shaken, 
and  the  appearance  of  the  milk,  its  odor,  taste,  etc.,  carefully 
noted  in  each  case. 

The  tubes  are  then  again  heated  in  the  tank  at  the  same  tem- 
perature as  before,  for  another  six  hours,  when  observations  of 
the  appearence  of  the  milk  in  each  tube  are  once  more  taken.  The 
tainted  milk  may  then  easily  be  discovered  by  the  abnormal 
coagulation  of  the  sample.  According  to  Gerber,1  good  and  prop- 
erly handled  milk  should  not  coagulate  in  less  than  twelve  hours, 
when  kept  under  the  conditions  described,  and  should  not  show 
anything  abnormal  when  coagulated,,  Milk  from  sick  cows  and 
from  cows -in  heat,  or  with  diseased  udders,  will  always  coagulate 
in  less  than  twelve  hours.  If  the  milk  does  not  curdle  within  a  day 
or  two,  it  should  be  tested  for  preservatives  (299). 

157.  The  Monrad  rennet  test  is  used  by  cheese  mak- 
ers for  determining  the  ripeness  of  milk.  Fig.  48  shows 
the  apparatus  used  in  the  test.  5  cc.  of  rennet  extract 
is  measured  into  a  50  cc.  flask  by  means  of  a  pipette; 
the  pipette  is  rinsed  with  water,  and  the  flask  filled  to 
the  mark  with  water.  160  cc.  of  milk  is  now  measured 
into  the  tin  basin  from  the  cylinder  and  slowly  heated 
to  exactly  86°  F.  5  cc.  of  the  dilute  rennet  solution  is 

1  Die  praktische  Milchpriifung,  p.  85. 


Testing  Milk  on  the  Farm. 


141 


then  quickly  added  to  the  warm  milk  and  the  time 
required  for  coagulation 
noted.1  Milk  sufficiently  ripe 
for  cheddar  cheese  making 
will  coagulate  in  30  to  60 
seconds,  according  to  the 
strength  of  the  rennet  ex- 
tract used. 

158.  The  Marschall  ren- 
net test  is  used  for  the  same 
purpose  as  the  Monrad  test. 

The  directions  for  this  test 
are  as  follows:  Fill  the  small 
glass  with  pure  water  to 
the  mark,  pour  into  it  one 
cc.  of  rennet  extract  and 
rinse  the  pipette  in  the  same 

FIG.  48.     The  Monrad  rennet  test    water.       Fill      the      CUp     with 

milk  to  the  zero  mark,  add  the  rennet,  mix  thoroughly 
and  allow  it  to  stand.  The  sweeter  the  milk  is,  the 
longer  it  will  take  to 
coagulate,  and  the  more 
milk  will  run  out  of  the 
cup  before  the  point  of 
coagulation  is  reached, 
when  the  flow  of  milk 
will  cease.  The  time  re- 
quired for  coagulating 
the  milk  is  shown  di- 
rectly by  a  Scale  On  the  FlG-  49-  Thc  Marschnll  rennet  test. 

inside  wall  of  the  cup  (see  fig.  49). 

1  Decker,  Cheese  Making-,  Revised  ed.,  1909,  p.   39. 


CHAPTER  IX. 
TESTING  MILK  ON  THE  FARM. 

159.  Variations  in  milk  of  single  cows.     The  varia- 
tions in  the  tests  of  milk  of  single  cows  from  milking  to 
milking  or  from  day  to  day,  are  greater  than  many 
cow-owners  suspect.     There  seems  to  be  no  uniformity 
in  this  variation,  except  that  the  quality  of  the  milk 
produced  generally  improves  with  the  progress  of  the 
period  of  lactation:  even   this  may  not  be  noticeable, 
however,  except  when  the  averages  of  a  number  of  tests 
made  at  different  stages  during  the  lactation  period  are 
compared  with  each  other.    When  a  cow  gives  her  maxi- 
mum quantity  of  milk,  shortly  after  calving,  the  qual- 
ity of  her  milk  is  generally  poorer  (by  one  per  cent,  of 
fat  or  less)   than  when  she  is  drying  off.     Strippers' 
milk  is  therefore,  as  a  rule,  richer  in  fat  than  the  milk 
of  fresh  cows. 

160.  By  testing  separately  every  milking  of  a  number 
of  cows  through  their  whole  period  of  lactation,   the 
results  obtained  have  seemed  to  warrant  the  following 
conclusions  in  regard  to  the  variations  in  the  test  of  the 
milk  from  single  cows,  and  it  is  believed  that  these  con- 
clusions allow  of  generalization.1 

1.  Some  cows  yield  milk  that  tests  about  the  same  at 
every  milking,  and  generally  give  a  uniform  quantity 
of  milk  from  day  to  day. 

1  Illinois  experiment  station,  bulletin  24. 


Testing  Milk  on  the  Farm.  143 

2.  Other  cows  give  milk  that  varies  in  an  unexplain- 
able  way  from  one   milking  to  another.     Neither  the 
morning  nor  the  evening  milking  is  always  the  richer, 
and  even  if  the  interval  between  the  two  milkings  is 
exactly  the  same,  the  quality  as  well  as  the  quantity  of 
milk  produced  will  vary  considerably.     Such  cows  are 
generally  of  a  nervous,  excitable  temperament,  and  are 
easily  affected  by  changes  in  feed,  drink,  or  surround- 
ing conditions. 

3.  The  milk  of  a  sick  cow,  or  of  a  cow  in  heat,  as  a 
rule,  tests  higher  than  when  the  cow  is  in  normal  con- 
dition ;  the  milk  yield  generally  decreases  under  such 
conditions ;   marked   exceptions  to  this  rule  have,  how- 
ever, been  observed. 

4.  Half -starved  or  underfed  cows  may  give  a  small 
yield  of  milk  testing  higher  than  when  the  cows  are 
properly  nourished,  probably  on  account  of  an  accom- 
panying feverish  condition  of  the  animal.    The  milk  is, 
however,  more  generally  of  an  abnormally  low  fat  con- 
tent, which  may  be  readily  increased  to  the  normal  per 
cent,  of  fat  by  liberal  feeding. 

5.  Fat  is  the  most  variable  constituent  of  milk,  while 
the  solids  not  fat  vary  within   comparatively  narrow 
limits.    The  summary  of  the  analyses  of  more  than  2400 
samples  of  American  milk  calculated  by  Cooke1  shows 
that  while  the  fat  content  varies  from  3.07  to  6.00  per 
cent.,  that  of  casein  and  albumen  varies  only  from  2.92 
to  4.30  per  cent,  or  less  than  one  and  one-half  per  cent.. 

1  Vermont  experiment  station,  report  for  1800.  p.  !><  :  Woll's  Hand- 
book for  Farmers  and  Dairymen,  Fifth  od..  p.  2.",0. 


144  Testing  MUk  and  Its  Products. 

and  the  milk  sugar  and  ash  content  increases  but  little 
(about  .69  per  cent.)  within  the  range  given. 

6.  A  test  of  only  one  milking  may  give  a  very  erro- 
neous impression  of  the  average  quality  of  a  certain 
cow's  milk.  A  composite  sample  (see  179)  taken  from 
four  or  more  successive  milkings  will  represent  the 
average  quality  of  the  milk  which  a  cow  produces  at 
the  time  of  sampling. 

161.  The  variations  that  may  occur  in  testing  the 
milk  of  single  cows,  are  illustrated  by  the  following  fig- 
ures obtained  in  an  experiment  made  at  the  Illinois  ex- 
periment station,1  in  which  the  milk  of  each  of  six  cows 
was  weighed  and  analyzed  daily  during  the  whole  period 
of  lactation.  Among  the  cows  were  pure-bred  Jerseys, 
Shorthorns  and  Holsteins,  the  cows  being  from  three  to 
eight  years  of  age  and  varying  in  weight  from  850  to 
1350  Ibs.  During  a  period  of  two  months  of  the  year2 
the  cows  were  i'ed  a  heavy  grain  ration  consisting  of 
twelve  Ibs.  of  corn  and  cob  meal,  six  Ibs.  of  wheat  bran, 
and  six  Ibs.  of  linseed  meal,  per  day  per  head.  This  sys- 
tem of  feeding  was  tried  for  the  purpose  of  increasing, 
if  possible,  the  richness  of  the  milk.  The  influence  of  this 
heavy  grain  feed,  as  well  as  that  of  the  first  pasture 
grass  feed,  on  the  quality  and  the  quantity  of  the  milk 
produced  is  shown  in  the  following  table,  which  gives 
the  complete  average  data  for  one  of  the  cows  (No.  3). 
The  records  of  the  other  cows  are  given  in  the  publica 
tion  referred  to ;  they  were  similar  to  the  one  here  given 
in  so  far  as  variations  in  quality  are  concerned. 

1  Bulletin  24. 
'See  175. 


Testing  Milk  on  the  Farm. 


145 


Average  results  obtained  in  weighing  and  testing  a 
milk  daily  during  one  period  of  lactation. 


Daily  milk 

Test  of 

Yield  of  fat 

yield 

one  day's  milk 

per  day 

MONTH 

1 
Id 

& 

!R 

^ 

|j 

IN 

11  "8 

a 

I 

.£ 

>~ 

^ 

*£ 

I  si 

^ 

it 

^5 

^ 

M 

13 

^ 

W 

S 

«!  n 

a  °- 

^C' 

^ 

H 

)3 

920 

12  1 

16  0 

10  0 

3  8 

4  9 

3  0 

46 

60 

34 

927 

16.0 

17.7 

14.0 

3.7 

4.6 

.59 

.76 

.44 

February 

1035 
1047 

16.1 
14  3 

17.7 
16  0 

13.5 
12  5 

5.8 
4  7 

fl'l 

.58 
54 

.84 
61 

.51 
50 

March 

April 

1054 

13.8 

16.5 

11.5 

4.0 

5.8 

g3.0 

.55 

.72 

.46 

May- 

1079 
1105 

14.5 
12  1 

14  0 

10.0 
9  2 

3.8 
3  g 

4.6 
4  6 

I''* 

.55 
47 

.70 
57 

.44 
35 

July 

1180 

9.3 

12.2 

6.0 

4.2 

6.2 

»9« 

.39 

.60 

.27 

1130 

6.4 

9.3 

3.5 

4.7 

7.9 

1.2.9 

.30 

.50 

.16 

162.  The  average  test  of  this  cow's  milk  for  her  whole 
period  of  lactation  was  3.8  per  cent,  of  fat  (i.  e.,  the 
total  quantity  of  fat  produced  -=-  total  milk  yield  X 
100)  ;  twice  during  this  time  the  milk  of  the  cow  tested 
as  high  as  5.8  per  cent.,  and  once  as  low  as  2.7  per  cent. 
The  average  weight  of  milk  produced  per  day  by  the 
cow  was  14  Ibs.;  this  multiplied  by  her  average  test, 
3.8,  shows  that  she  produced  on  the  average  .53  lb.,  or 
about  one-half  of  a  pound,  of  butter  fat  per  day  during 
her  lactation  period.  If,  however,  her  butter-producing 
capacity  had  been  judged  by  the  test  of  her  milk  for 
one  day  only,  this  test  might  have  been  made  either  on 
the  day  when  her  milk  tested  5.8  per  cent.,  or  when  it 
was  as  low  as  2.7  per  cent.  Both  of  these  tests  were 
made  in  mid-winter  when  the  cow  gave  about  16  Ibs.  of 
milk  a  day.  Multiplying  this  quantity  by  .058  gives  .93 
lb.  of  fat,  and  by  .027  gives  .43  lb.  of  fat.  Either 


146  Testing  Milk  and  Its  Products. 

result  would  show  the  butter  fat  produced  by  the  cow  on 
certain  days,  but  neither  gives  a  correct  record  of  her 
actual  average  daily  performance  for  this  lactation 
period. 

A  sufficient  number  and  variety  of  tests  of  the  milk 
of  many  cows  have  been  made  to  prove  that  there  is 
no  definite  regularity  in  the  daily  variations  in  the 
richness  of  the  milk  of  single  cows.  The  only  change  in 
the  quality  of  milk  common  to  all  cows  is,  as  stated, 
the  natural  increase  in  fat  content  as  the  cows  are  dry- 
ing off,  and  even  in  this  case  the  improvement  in  the 
quality  of  the  milk  sometimes  does  not  occur  until  the 
milk  yield  has  decreased  very  materially. 

163.  Causes  of  variations  in  fat  content.   The  qual- 
ity of  a  cow's  milk  is,  as  a  rule,  decidedly  influenced  by 
the  following  conditions: 

Length  of  interval  between  milkings. 

Change  of  feed. 

Change  of  milkers. 

Rapidity  of  milking. 

Exposure  to  rain  or  bad  weather. 

Rough  treatment. 

Unusual  excitement  or  sickness. 

164.  Disturbances  like  those  enumerated   frequently 
increase  the  richness  of  the  milk  for  one,  and  some- 
times for  several  milkings,  but  a  decrease  in  quality  fol- 
lows during  the  gradual  return  to  normal  conditions, 
and  taken  as  a  whole  there  is  a  considerable  falling  off 
in  the  total  production  of  milk  and  butter  fat  by  the 
cow,  on  account  of  the  nervous  excitement  which  she 
has  gone  through.     Aside   from  changes  due  to  well- 


Testing  Milk  on  the  Farm.  147 

definable  causes  like  those  given  above,  the  quality  of 
some  cows'  milk  will  often  change  considerably  without 
any  apparent  cause.  The  dairyman  who  is  in  the  habit 
of  making  tests  of  the  milk  of  his  individual  cows  at 
regular  intervals  will  have  abundant  material  for  study 
in  the  results  obtained,  and  he  will  soon  be  able  to  tell 
from  the  tests  made,  if  these  are  continued  for  several 
days,  whether  or  not  the  cows  are  in  a  normal  healthy 
condition  or  have  been  subjected  to  excitement  or  abuse 
in  any  way. 

165.  Number  of  tests  required  during  a  period  of 
lactation  in  testing  cows.     The  daily  records  of  the 
six  cows  referred  to  on  page  142  furnish  data  for  com- 
paring their  total  production  of  milk  and  butter  fat  dur- 
ing one  period  of  lactation,  as  found  from  the  daily 
weights  and  tests  of  their  milk,  with  the  total  amount 
calculated  from  weights  and  tests  made  at  intervals  of 
7,  10,  15  or  30  days.     The  averages  of  all  results  ob- 
tained with  each  of  the  six  cows  show  that  weighing  and 
testing  the  milk  of  a  cow  every  seventh  day  gave  98  per 
cent,  of  the  total  milk  and  butter  fat,  which  according 
to  her  daily  record  was  the  total  product.     Tests  made 
one  day  every  two  weeks  gave  97.6  per  cent,  of  the 
total  milk,  and  98.5  per  cent,  of  the  total  butter  fat, 
and  tests  made  one  day  per  month,  or  only  ten  times 
during  the  period  of  lactation,  gave  96.4  per  cent,  of 
the  total  milk,  and  97  per  cent,  of  the  total  production 
of  butter  fat. 

1 66.  The  record  of  one  of  the  cows  will  show  how 
these  calculations  are  made:     It  was  found  from  the 
daily  weights  and  tests  that  cow  No.  1,  in  one  lactation 

period  of  307  days,  gave  5,044  Ibs.  of  milk  which  con- 


148 


Testing  Milk  and  Its  Products. 


tained  254  Ibs.  of  butter  fat.  Selecting  every  thirtieth 
day  of  her  record  as  testing  day,  the  total  production  of 
milk  and  fat  is  shown  to  be  as  follows: 

Production  of  milk  and  butter  fat  per  day. 


Testing  day 

Weight  of  Milk 

Test  of  milk 

Yield  of  butter  fat 

Nov      4 

20.5 

4.7 

96 

Dec       4         __  __. 

18.7 

4.6 

.86 

Jan       3 

17  7 

4.9 

.86 

Feb       2 

20.0 

45 

.90 

Mar.     3 

18.2 

4.7 

.86 

April     2 

19.5 

4.4 

.81 

May      2 

17  7 

4.8 

85 

13  1 

5  5 

72 

July      1  _ 

12.2 

6.2 

.76 

July    31 

3  2 

7.2 

23 

Total 

160  8  Ibs 

7  81  Ibs 

Average   per   day_. 

16.08  Ibs. 

4.85 

.78  Ib. 

The  average  daily  production  of  the  cow,  according 
to  the  figures  given  in  the  preceding  table,  was  about 
16  Ibs.  of  milk,  containing  .78  Ib.  of  butter  fat.  Multi- 
plying these  figures  by  307,  the  number  of  days  during 
which  the  cow  was  milked,  gives  4,912  Ibs.  of  milk  and 
240  Ibs.  of  fat.  This  is  132  Ibs.  of  milk  and  14  Ibs.  of 
fat  less  than  the  total  weights  of  milk  and  butter  fat,  as 
found  by  the  daily  weights  and  tests,  or  2.8  and  5.5  per 
cent,  less,  for  milk-  and  fat  production,  respectively. 
This  is,  however,  calculated,  from  only  ten  single  weights 
and  tests,  while  it  required  over  600  weighings  and  300 
tests  of  the  milk  to  obtain  the  exact  amount. 

Similar  calculations  from  the  records  of  the  other 
cows  gave  fully  as  close  results,  showing  that  quite  sat- 


Testing  Milk  on  the  Farm.  149 

isfactory  data  as  to  the  total  production  of  milk  and 
butter  fat  of  a  cow  may  be  obtained  by  making  correct 
weighings  and  tests  of  her  full  day's  milk  once  every 
thirty  days. 

i66a.  Official  tests  of  dairy  cows.  The  various  ex- 
periment stations  conduct  tests  of  dairy  cows  for  breed- 
ers and  farmers,  by  which  means  records  of  production 
of  milk  and  butter  fat  are  obtained  for  periods  of  7  or 
30  days,  or  for  an  entire  year.  This  system  of  official 
testing  is  described  in  bulletins  issued  by  several  sta- 
tions.1 

167.  When  to  test  a  cow.  The  Vermont  experi- 
ment station  for  several  years  made  a  special  study  of 
the  question  when  a  cow  should  be  tested  in  order  to 
give  a  correct  idea  of  the  whole  year's  production,  when 
only  one  or  two  tests  are  to  be  made  during  the  lacta- 
tion period.2  The  results  obtained  may  be  briefly  sum- 
marized as  follows: 

a.  As  to  quality  of  milk  produced.  If  two  tests  of 
each  cow's  milk  are  to  be  made  during  the  same  lacta- 
tion period,  it  is  recommended  to  take  composite  sam- 
ples at  the  intervals  given  below. 


FIRST  SAMPLE 

SECOND   SAMPLE 

For  spring  cows, 
For  summer  " 
For  fall          " 

6  weeks  after  calving 
8      " 
8-10"         "         " 

6^-7%  mos.  after  calving 
6     -7        "      " 
5^-7        "      "          " 

If  only  one  test  is  to  be  made,  approximately  correct 
results  may  be  obtained  by  testing  the  milk  during  the 

1  See,  e.  g.,  Wis.  exp.  station  bull.  191  and  242 ;  also  bull.  226,  The 
Wisconsin   Dairy  Cow   Competition,  and   research  bull.   26,   Studies  in 
Dairy   Production,   published  by  this  station. 
1  Sixth  report,  1882,  p.  106;  Ninth  report,  1895,  p.  176. 


150  Testing  Milk  and  Its  Products. 

sixth  month  from  calving,  in  case  of  spring  cows;  dur- 
ing the  third  to  fifth  month  in  case  of  sunnner-calving 
cows,  and  during  the  fifth  to  seventh  month  for  fall- 
calving  cows. 

In  all  cases  composite  samples  of  the  milk  for  at  least 
two  days  should  lie  taken  (,10'J).  "The  test  of  a  single 
sample,  drawn  from  a  single  milking  or  day,  will  not  of 
necessity,  or  indeed  usually,  give  trustworthy  results." 
b.  As  to  quantity  of  milk  produced.  The  milk  may 
be  weighed  for  two  days  in  the, middle  of  the  month, 
and  the  entire  month's  yield  obtained  with  considerable 
accuracy  (barring  sickness  and  drying  off), 
by  multiplying  the  sum  by  a  factor,  ac- 
cording to  the  number  of  days  in  the  dif- 
ferent months.  The  weighing  is  read- 
ily done  by  means  of  a  spring  balance,  the 
hand  of  which  is  set  back  so  that  the  empty~ 
pail  brings  it  to  zero  (fig.  50).  If  several 
pails  are  to  be  used,  they  should  first  be 
made  to  weigh  the  same  by  putting  a  little 
solder  on  the  lighter  pails.  Milk  scales 
which  weigh  and  automatically  register  the 
yield  of  milk  from  twenty  cows  have  been 
„  placed  on  the  market,  but  so  far  as  known 

1*  IG.  oU.       .Milk 

scnie.  have  not  proved  satisfactory. 
168.  Sampling  milk  of  single  cows.  In  sampling 
the  milk  of  single  cows,  all  the  milk  obtained  at  the 
milking  must  be  carefully  mixed,  by  pouring  it  from 
one  vessel  to  another  a  few  times,  or  stirring  it  thor- 
oughly by  means  of  a  dipper  moved  up  and  down,  as 
well  as  horizontally,  in  the  pail  or  can  in  which  it  is 


Testing  Milk  on  the  Farm.  151 

held;  a  sample  for  testing  purposes  is  then  taken  at 
once.  A  correct  sample  of  a  cow's  milk  cannot  be  ob- 
tained by  milking  directly  into  a  small  bottle  from  one 
teat,  or  by  filling  the  bottle  with  a  little  milk  from  each 
teat,  or  by  taking  some  of  the  first,  middle  and  last  milk 
drawn  from  the  udder.  Such  samples  cannot  possibly 
represent  the  average  quality  of  the  milk  of  one  entire 
milking,  since  there  is  as  much  difference  between  the 
first  and  the  last  portions  of  a  milking,  as  between  milk 
and  cream.1  Lack  of  care  in  taking  a  fair  sample  is 
the  cause  of  many  surprising  results  obtained  in  testing 
the  milk  of  single  cows. 

169.  Composite  samples.  When  a  cow  is  to  be  tested 
for  milk  production  she  should  be  milked  dry  the  last 
milking  previous  to  the  day  when  the  test  is  to  be  made. 
The  entire  quantity  of  milk  obtained  at  each  milking  is 
mixed  and  sampled  separately.  On  account  of  the  vari- 
ations in  the  composition  of  the  milk,  a  number  of  tests 
of  successive  milkings  must  be  made.  As  this  involves 
considerable  labor,  the  plan  of  taking  composite  samples 
is  preferable ;  the  method  of  composite  sampling  and  test- 
ing is  explained  in  detail  under  the  second  subdivision  of 
Chapter  X  (180) ;  suffice  it  here  to  say  that  the  method 
followed  in  the  case  of  single  cows'  or  herd  milk  is  to 
take  about  an  ounce  of  the  thoroughly  mixed  milk  of 
each  milking;  this  is  placed  in  a  pint  or  quart  glass  jar 
containing  a  small  quantity  of  some  preservative,  prefer- 
ably about  half  a  gram  (8  grains)  of  powdered 
potassium  bi-chromate.  If  a  number  of  composite  sam- 
ples of  the  milk  of  single  cows  are  taken,  each  jar  should 

1  Agricultural  Science,  6,  pp.  540-42. 


152  Testing  Milk  and  Its  Products. 

be  labeled  with  the  number  or  name  of  the  particular 
cow.  Composite  tests  are  generally  taken  for  two  or  four 
days  or  for  a  week.  If  continued  for  a  week,  the  jars  will 
contain  at  the  end  of  this  time  a  mixture  of  the  milk 
of  fourteen  milkings.  The  composite  sample  is  then 
carefully  mixed  by  pouring  it  gently  a  few  times  from 
one  jar  to  another,  and  is  tested  in  the  ordinary  man- 
ner. The  result  of  this  test  shows  the  average  quality 
of  the  milk  produced  by  the  cow  during  the  time  the 
milk  was  sampled. 

As  the  amounts  as  well  as  the  quality  of  the  milk  pro- 
duced by  single  cows  vary  somewhat 'from  day  to  day 
and  from  milking  to  milking,  it  is  desirable  in  testing 
single  cows,  especially  when  the  test  includes  only  a  few 
days,  to  take  a  proportionate  part  (an  aliquot}  of  each 
milking  for  the  composite  test  sample.  This  is  easily 
done  by  means  of  a  Scovell  sampling  tube,  the  use  of 
which  is  explained  in  another  place  (183),  or  by  a  25  cc. 
pipette  divided  into  _1  cc. ;  in  using  the  latter  appara- 
tus as  many  cubic  centimeters  and  tenths  of  a  cubic 
centimeter  of  milk  are  conveniently  taken  each  time  for 
the  composite  sample  as  the  weight  of  milk  in  pounds 
and  tenths  of  a  pound  produced  by  the  cow.1 

170.  Testing  warm  milk.  The  opinion  is  some- 
times expressed  that  a  -considerable  error  is  intro- 
duced by  measuring  out  milk  warm  from  the  cow 
for  the  Babcock  test,  since  milk  expands  on  being 
warmed,  and  a  too  small  quantity  is  obtained  in 
this  manner.  By  calculation  of  the  expansion  of 
milk  between  different  temperatures  it  is  found  that 

1  Decker,  Wis.  experiment  station,  report  16,  p.  155. 


Testing  Milk  on  the  Farm.  153 

1  cc.  of  milk  at  17.5°  C.  (room  temperature)  will 
have  a  volume  of  1.006289  cc.  at  37°  C.  (blood-heat), 
i.  e.,  an  error  of  less  than  .03  per  cent,  is  introduced  by 
measuring  out  milk  of  ordinary  quality  at  the  latter 
temperature.  While  the  temperature  has  therefore  prac- 
tically no  importance,  the  air  incorporated  in  the  milk 
during  the  milking  process  will  introduce  an  appreci- 
able error  in  the  testing,  and  samples  of  milk  should 
therefore  be  left  for  an  hour  or  more  after  milking  be- 
fore the  milk  is  measured  into  the  test  bottles.  By  this 
time  the  specific  gravity  of  the  samples  can  also  be  cor- 
rectly determined  (113). 

171.  Size  of  the  testing  sample.    Four  ounces  are  a 
sufficient  quantity  for  a  sample  of  milk  if  it  is  desired 
to  determine  its  per  cent,  of  fat  only ;  if  the  milk  is  to 
be  tested  with  a  lactometer,  when  adulteration  is  sus- 
pected, about  a  pint  sample  is  needed.   If  this  sample  of 
milk  is  put  into  a  bottle  and  carried  or  sent  away  from 
the  farm  to  be  tested,  the  bottle  should  be  filled  with  milk 
clear  up  to  the  neck  to  prevent  a  partial  churning  of 
butter  in  the  sample  during  transportation  (30). 

172.  Variations   in  herd  milk.     While  considerable 
variations  in  the  quality  of  the  milk  of  single  cows  are 
often  met  with,  a  mixture  of  the  milk  of  several  cows, 
or  of  a  whole  herd,  is  comparatively  uniform  from  day 
to  day;  the  individual  differences  tend  to  balance  each 
other  so  that  variations,  when  they  do  occur,  are  less 
marked  than  in  case  of  milk  of  single  cows.    There  are, 
however,  at  times  marked  variations  also  in  the  test  of 
herd  milk  on  successive  days ;  the  following  figures  from 
the  dairy  tests  conducted  at  the  World's  Columbian  Ex- 


154 


Testing  Milk  and  Its  Products. 


position  in  Chicago  in  1893  illustrate  the  correctness  of 
this  statement.  The  tests  included  twenty-five  Jersey 
and  Guernsey  cows  each  and  twenty- four  Shorthorn 
cows. 

Tests  of  herd  milk  on  successive  days. 


Date 

Jersey 

Guernsey 

Shorthorn 

July  16    1893 

4  8   per  cent. 

4  6   per  cent. 

3  8  per  cent 

July  17,  1893  

5.0         " 

4.5         " 

3.8         " 

July  18,  1893 

47         " 

4.4         " 

3.8         " 

July  19,  1893 

46         " 

46         " 

37         " 

July  20,  1893     _   _ 

5.0         " 

4.5         " 

3.8         '  '• 

On  July  17,  1893,  the  mixed  milk  of  the  Jersey  cows 
tested  two-tenths  of  one  per  cent,  higher  than  on  the 
preceding  day ;  the  Guernsey  herd  milk  tested  one-tenth 
of  one  per  cent,  lower,  while  the  Shorthorn  milk  did  not 
change  in  composition ;  comparing  the  tests  on  July  19 
and  20,  we  find  that  the  Jersey  and  Shorthorn  milk 
tested  four-tenths  and  one-tenth  of  one  per  cent,  higher, 
respectively,  on  the  latter  day  than  on  the  former,  and 
the  Guernsey  milk  tested  one-tenth  of  one  per  cent, 
lower.  There  was  no  change  in  the  feed  of  the  cows  or 
in  the  method  of  handling  them  on  these  days. 

173.  Ranges  in  variations  of  herd  milk.  According 
to  Pleischmann,1  the  composition  of  herd  milk  will  vary 
on  single  days  from  the  average  values  for  the  year, 
expressed  in  per  cent,  of  the  latter,  as  follows: 

The  specific  gravity  (expressed  in  degrees)  may  go  above  or 
below  the  yearly  average  by  more  than  10  per  cent. 

The  per  cent,  of  fat  may  go  above  or  below  the  yearly  aver- 
age b^y  more  than  30  per  cent. 

1  Book  of  the  Dairy,  p.  32. 


Testing  the  Purity  of  Milk.  155 

The  per  cent,  of  total  solids  may  go  above  or  below  the  yearly 
average  by  more  than  14  per  cent. 

The  per  cent,  of  solids  not  fat*  may  go  above  or  below  the 
yearly  average  by  more  than  10  per  cent. 

To  illustrate,  if  the  average  test  of  a  herd  during  a  whole 
period  of  lactation  is  4.0  per  cent.,  the  test  on  a  single  day  may 
exceed  4.0+  ^  X  4.0=5.2,  or  may  go  below  2.8  per  cent,  (viz., 
4.0—  ^  X4.0)  ;  if  the  average  specific  gravity  is  1.031  (lacto- 
meter degrees,  31  )*  the  specific  gravity  of  the  milk  on  a  single 
day  may  vary  between  1.0279  and  1.0341  (31+Ty>0  X31=34.1; 
31—  jiA,  x 31=27.9). 

174.  Influence  of  heavy  grain-feeding  on  the  qual- 
ity of  milk.     If  cows  are  not  half-starved  or  underfed, 
an  increase  in  the  feeding  ration   will  not  materially 
change  the  richness  of  the  milk  produced;  this  has  been 
shown  by  numerous  careful   feeding  experiments  con- 
ducted under  a  great  variety  of  conditions  and  in  many 
countries,     Good  dairy  cows  will  almost  invariably  give 
more  milk  when  their  rations  are  increased,  so  long  as 
they  are  not  overfed,  but  the  milk  will  remain  of  about 
the  same  quality  after  the  first  few  days  are  passed  as 
before  this  time,  provided  the  cows  are  in  good  health 
and  under  normal  conditions.     Any  change  in  the  feed 
of  cows  will  usually  bring  about  an  immediate  change 
in  the  fat  content  of  the  milk,  as  a  rule  increasing  it  to 
some  extent,  but  in  the  course  of  a  few  days,  when  the 
cows  have  become  accustomed  to  their  new  feed,  the  fat 
content  will  again  return  to  its  normal  amount. 

175.  The  records  of  the  cows  included  in  the  feeding 
experiment  at  the  Illinois  station,  to  which   reference 
has  been  made  on  p.  144,  furnish  illustrations  as  to  the 
effect  of  heavy  feeding  on  the  quality  of  milk.     The 

1  See  page  103. 


156  Testing  Milk  and  Its  Products. 

feed,  as  well  as  the  milk  of  the  cows,  was  weighed  each 
day  of  the  experiment.  During  the  month  of  December 
each  cow  was  fed  a  daily  ration  consisting  of  10  Ibs.  ol 
timothy  hay,  20  Ibs.  of  corn  silage  and  2  Ibs.  of  oil  meal ; 
the  table  on  p.  145  shows  that  cow  No.  3  produced  on 
this'  feed  an  average  of  12.1  Ibs.  of  milk,  testing  3.8  per 
cent,  of  fat.  In  January  the  grain  feed  was  gradually 
increased  until  the  ration  consisted  of  12  Ibs.  of  timothy 
hay,  8  Ibs.  of  corn  and  cob  meal,  4  Ibs.  of  wheat  bran, 
and  4  Ibs.  of  oil  meal.  All  the  cows  gained  in  milk  on 
this  feed ;  cow  No.  3  thus  gave  an  average  of  4  Ibs.  more 
milk  per  day  in  January  than  in  December,  but  the 
average  test  of  her  milk  was  3.7  per  cent.,  or  one-tenth 
of  one  per  cent,  lower  than  during  the  preceding  month. 
The  heavy  grain-feeding  was  continued  through  Febru- 
ary and  March,  when  it  reached  12  Ibs.  of  timothy  hay, 
12  Ibs.  of  corn  and  cob  meal,  6  Ibs.  of  wheat  bran  and 
6  Ibs.  of  oil  meal  per  day.  The  records  show  that  the 
flow  of  milk  kept  up  to  16  Ibs.  per  day  in  February  in 
case  of  this  co'w,  but  fell  to  14  Ibs.  in  March  and  April, 
the  average  test  of  the  milk  being,  in  February  3.6,  in 
March  3.8,  and  in  April  4.0  per  cent.  The  milk  was, 
therefore,  somewhat  richer  in  April  than  in  December, 
but  not  more  so  than  is  found  normally,  owing  to  the 
progress  of  the  period  of  lactation. 

176.  Influence  of  pasture  on  the  quality  of  milk. 
On  May  1,  the  cows  were  given  luxuriant  pasture  feed 
and  no  grain ;  a  slight  increase  in  the  average  amount  of 
milk  produced  per  day  followed,  with  a  reduction  in 
the  test,  this  being  3.8  per  cent,  the  same  as  in  De- 
cember. 


Testing  Milk  on  the  Farm.  157 

During  all  these  changes  of  feed  there  was,  therefore, 
not  much  change  in  the  richness  of  the  milk,  while  the 
flow  of  milk  was  increased  by  the  heavy  grain  feeding 
for  several  months,  as  well  as  by  the  change  from  grain- 
feeding  in  the  barn  to  pasture  feed  with  no  grain.1  As 
a  general  rule,  the  test  of  the  milk  will  be  increased  by 
a  few  tenths  of  a  per  cent,  during  the  first  couple  of 
weeks  after  the  cows  have  been  turned  out  to  pasture 
in  the  spring.  The  increase  is  perhaps  due  as  much  to 
the  stimulating  influence  of  out-door  life  after  the  con- 
finement in  the  stable  during  the  winter  and  spring,  as 
to  the  change  in  the  feed  of  the  cows.  After  a  brief 
period  the  milk  will  again  change  back  to  its  normal  fat 
content. 

177.  The  increase  which  has  often  been  observed  in 
the  amount  of  butter  produced  by  a  cow,  as  a  result  of 
a  change  in  feed,  doubtless  as  a  rule  comes  from  the 
fact  that  more,  but  not  richer  milk  is  produced.  The 
quality  of  milk  which  a  cow  produces  is  as  natural  to 
her  as  is  the  color  of  her  hair  and  is  not  materially 
changed  by  any  special  system  of  normal  feeding.2 

lFor  further  data  on  this  point,  see  Cornell  (N.  Y.)  exp.  sta.  bulle- 
tins 13,  22,  36  and  49;  N.  D.  exp.  sta.,  bull.  16;  Kansas  exp.  sta.,  re- 
port, 1888 ;  Hoard's  Dairyman,  1896,  pp.  924-5  ;  W.  Va.  exp.  sta.,  b. 
109. 

-  On  this  point  numerous  discussions  have  taken  place  in  the  past  In 
the  agricultural  press  of  this  and  foreign  countries,  and  the  subject 
has  been  under  debate  at  nearly  every  gathering  of  farmers  where  feed- 
ing problems  have  been  considered.  Many  farmers  are  firm  In  their  be- 
lief that  butter  fat  can  be  "fed  into"  the  milk  of  a  cow,  and  would  take 
exception  to  the  conclusion  drawn  In  the  preceding.  The  results  of 
careful  investigations  by  our  best  dairy  authorities  point  conclusively, 
however,  in  the  direction  stated,  and  the  evidence  on  this  point  is  over- 
whelmingly against  the  opinion  that  the  fat  content  of  the  milk  can  be 
materially  and  for  any  length  of  time  increased  by  changes  in  the  sys- 
tem of  feeding.  The  most  conclusive  evidence  in  this  line  is  perhaps 


158  Testing  Milk  and  Its  Products. 

178.  Method   of   improving    the   quality   of    milk. 

The  quality  of  the  milk  produced  by  a  herd  can  gener- 
ally be  improved  by  selection  and  breeding,  i.  e.,  by  dis- 
posing of  the  cows  giving  poor  milk,  say  below  3  per 
cent,  of  fat,  and  by  breeding  to  a  pure-bred  bull  of  a 
strain  that  is  known  to  produce  rich  milk.  This  method 
cannot  work  wonders  in  a  day,  or  even  in  a  year,  but  it 
is  the  only  certain  way  we  have  of  improving  the  qual- 
ity of  the  milk  produced  by  our  cows. 

It  may  be  well  in  this  connection  to  call  attention  to 
the  fact  that  the  quality  of  the  milk  which  a  cow  pro- 
duces is  only  one  phase  of  the  question ;  the  quantity  is 
another,  and  an  equally  important  one.  Much  less  dis- 
satisfaction and  complaint  about  low  tests  among  pat- 
rons of  creameries  and  cheese  factories  would  arise  if 
this  fact  was  more  generally  kept  in  mind.  A  cow  giv- 
ing 3  per  cent,  milk  should  not  be  condemned  because 
her  milk  does  not  test  5  per  cent. ;  she  may  give  twice 
as  much  milk  per  day  as  a  5  per  cent  cow,  and  will 
therefore  produce  considerably  more  butter  fat.  The 
point  whether  or  not  a  cow  is  a  persistent  milker  is  also 
of  primary  importance ;  a  production  of  300  Ibs.  of  but- 
ter fat  during  a  whole  period  of  lactation  is  a  rather 
high  dairy  standard,  but  one  reached  by  many  herds, 

the  Danish  co-operative  cow-feeding  experiments,  conducted  during  the 
nineties  with  over  2,000  cows  in  all.  The  conclusion  arrived  at  by  the 
Copenhagen  experiment  station,  under  whose  direction  the  experiments 
have-been  conducted,  is :  that  the  changes  of  feed  made  in  the  different 
lots  of  cows  included  on  the  experiments  had  practically  no  influence 
on  the  chemical  composition  (the  fat  content)  of  the  milk  produced.  In 
these  experiments  grain  feeds  were  fed  against  roots,  oil  cake,  wheat 
bran  or  shorts ;  grain  and  oil  cake  were  furthermore  fed  against  roots, 
and  roots  were  given  as  an  additional  feed  to  the  standard  rations 
tried, — in  all  case?  with  practically  negative  results  so  far  as  changes 
in  the  fat  contents  of  the  milk  produced  are  concerned. 


Testing  Milk  on  the  Farm.  159 

as  the  average  for  all  mature  cows  in  the  herd. 
It  should  be  remembered  that  a  high  production  of  but- 
ter fat  in  the  course  of  the  whole  period  of  lactation  is 
of  more  importance  than  a  very  high  test. 


Questions. 

1.  How  does  the  test  of  the  milk  yielded  by  a  cow  generally 
change  with  the  advance  of  the  period  of  lactation! 

2.  Mention  at  least  six  causes  of  variations  in  the  test  of  a 
cow's  milk. 

3.  How  is  an  accurate  sample  taken  of  a  cow's  milkf 

4.  Between  which  limits   is  the  test  of  milk  of  single  cows 
and  of  a  herd  likely  to  vary? 

5.  Will  it  introduce  any  error  in  the  test  of  a  cow's  milk  to 
measure  out  the  sample  directly  after  milking  ?If  so,  how  much? 

6.  How  many  times  should  the  milk  of  a  cow  be  weighed  and 
tested  to  calculate  the  total  production  of  milk  and  butter  fat 
by  the  cow  during  a  whole  period  of  lactation! 

7.  What  is  an  official  test  of  a  cow? 

8.  How  does  the  test,  as  a  general  rule,  change  during  the 
first  couple  of  weeks  after  the  cows  are  let  out  on  pasture  in  the 
the  spring? 

9.  How  do  changes  in  the  feed  of  a  cow  influence  the  quan- 
tity and  the  quality  of  her  milk? 


CHAPTER  X. 


COMPOSITE  SAMPLES  OF  MILK. 

179.  Shortly  after  milk  testing  had  been  introduced 
to  some  extent  in  creameries  and  cheese  factories,  it  was 
suggested  by  Patrick,  then  of  the  Iowa  experiment  sta- 
tion,1 that  a  great  saving  in  labor,  without  affecting 

the  accuracy  of  the 
results,  could  be  ob- 
tained by  testing  a 
mixture  of  the  daily 
samples  of  milk  from 
one  source,  instead  of 
each  one  of  these 
samples.  Such  a  mix- 
ture is  called  a  com- 
posite sample.  The 
usual  methods  of  tak- 
ing such  samples  at 
creameries  and  cheese 
factories  are  as  fol- 
lows: 

180.    Methods     of 
taking   composite 

aklng  test  samples  at  ta-takc.       samp,es.       &     Uge    of 

tin  dipper.  Either  pint  or  quart  fruit  jars,  or  milk  bot 
ties  provided  with  a  cover,  are  used  for  receiving  the 
daily  samples.  One  of  these  jars  is  supplied  for  each 

'Bulletin  9,  May  1890. 


Composite  Samples  of  Milk.  161 

patron  of  the  factory  and  is  labeled  with  his  name  or 
number.  A  small  quantity  of  preservative  (bi-chromate 
of  potash,  corrosive  sublimate,  etc.,  see  190)  is  added  to 
each  jar;  these  are  placed  on  shelves  or  somewhere 
within  easy  reach  .of  the  operator  who  inspects  and 
weighs  the  milk  as  it  is  received  at  the  factory.  When 
all  the  milk  delivered  by  a  patron  is  poured  into  the 
weighing  can  and  weighed,  a  small  portion  thereof, 
usually  about  an  ounce,  is  put  into  the  jar  labeled  with 
the  name  or  number  of  the  patron.  The  samples  are 
conveniently  taken  by  means  of  a  small  tin  dipper  hold- 
ing about  an  ounce.  This  sampling  is  continued  for  a 
week,  ten  days,  or  sometimes  two  weeks,  a  portion  of 
each  patron's  milk  being  added  to  his  particular  jar 
every  time  he  delivers  milk.  A  test  of  these  composite 
samples  takes  the  place  of  separate  daily  tests  and  gives 
information  regarding  the  average  quality  of  the  milk 
delivered  by  each  patron  during  the  period  of  sampling. 
The  weight  of  butter  fat  which  each  patron  brought 
to  the  factory  in  his  milk  during  this  time,  is  obtained 
by  multiplying  the  total  weight  of  milk  delivered  dur- 
ing the  sampling  period  by  the  test  of  the  composite 
sample,  dividing  the  product  by  100. 

181.  This  method  of  taking  composite  samples  has 
been  proved  to  be  practically  correct.  It  is  absolutely 
correct  only  when  the  same  weight  of  milk  is  delivered 
daily  by  the  patron.  If  this  is  not  the  case,  the  size  of 
the  various  small  samples  should  bear  a  definite  relation 
to  the  milk  delivered;  one  sixteen-hundredth,  or  one 
two-thousandth  of  the  amount  of  milk  furnished  should, 
for  instance,  be  taken  for  thp  composite  sample  from 


162  Testing  Milk  and  Its  Products. 

each  lot  of  milk.  This  can  easily  be  done  by  means  of 
special  sampling  devices  (see  182  et  seq.).  As  the  quan- 
tities of  the  milk  delivered  from  day  to  day  by  each 
patron  vary  but  little,  perhaps  not  exceeding  10  per 
cent,  of  the  milk  delivered,  the  error  introduced  by 
taking  a  uniform  sample,  e.  g.,  an'  ounce  of  milk,  each 
time  is,  however,  small  and  it  may  not  be  necessary  to 
take  cognizance  of  it  in  factory  work.  This  method  of 
composite  sampling  described  is  quite  generally  adopted 
in  separator  creameries  and  cheese  factories,  where  the 
payment  for  the  milk  is  based  on  its  quality. 

In  order  to  obtain  reliable  results  by  composite  sam- 
pling it  is  essential  that  each  lot  of  milk  sampled  shall 
be  sweet  and  in  good  condition,  containing  no  lumps  of 
curdled  milk  or  butter  granules.  The  milk  should  of 
course  always  be  evenly  mixed  before  the  sample  is 
taken. 

182.  b.  Drip  sample.  Composite  samples  are  some- 
times taken  at  creameries  and  cheese  factories  by  col- 
lecting in  a  small  dish  the  milk  that  drips  through  a 
fine  hole  in  the  bottom  of  the  conductor  spout  through 
which  the  milk  runs  from  the  weighing  can  to  the  re- 
ceiving vat  or  tank.  A  small  portion  of  the  drip  col- 
lected each  day  is  placed  in  the  composite  sample  jar, 
or  the  quantity  of  drip  is  regulated  so  that  all  of  it 
may  be  taken.  In  the  latter  case  the  quantity  of  milk 
delivered  will  enter  into  the  composite  sampling  as  well 
as  its  quality  and  the  sample  from,  say  200  Ibs.  of  milk, 
will  be  twice  as  large  as  the  sample  from  100  Ibs.  of  milk. 

Where  it  is  desired  to  vary  the  size  of  samples  accord- 
ing to  the  quantity  of  milk  delivered  from  day  to  day, 


Composite  Samples  of  Milk.  163 

it  is  necessary  to  adopt  the  method  of  collecting  drip 
samples  just  explained,  or  to  make  use  of  special  sam- 
pling devices,  like  the  "milk  thief,"  the  Scovell,  Equity, 
McKay,   and    Michels    sampling    tubes.1      The 
principle  of  these  tubes  is  the  same,  and  it  will 
be  sufficient  to  describe  here  only  a  few  of  them 
183.  c.  The   Scovell    sampling    tube.      This 
convenient  device  for  sampling  milk2   (fig.  52) 
consists  of  a  drawn  copper  or  brass  tube,  one- 
half  to  one  inch  in  diameter ;  it  is  open  at  both 
ends,  the  lower  end  sliding  snugly  in  a  cap  pro- 
vided with  three  elliptical  openings  at  the  side, 
through  which  the  milk  is  admitted.     The  milk 
to  be  sampled  is  poured  into  a  cylindrical  pail, 
or  the  factory  weighing  can,  and  the  tube,  with 
the  cap  set  so  that  the  apertures  are  left  open, 
is   lowered   into  the  milk  until   it  touches   the 
bottom  of  the  can.     The  tube  will  be  filled  in- 
stantly to  the  level  of  the  milk  in  the  can  and 
is  then  pushed  down  against  the  bottom  of  the 
can,  thereby  closing  the  apertures  of  the   cap 
and  confining  within  the  tube  a  column  of  milk   Scovell 
representing   exactly   the   quality   of   the   milk  saSmKng 
in  the  can  and  forming  an  aliquot  part  thereof. 
The  milk  in  the  sampling  tube  is  then  emptied  into  the 
composite  sample  jar  by  turning  the  tube  upside  down 

JA  recent  Wisconsin  law  (Chap.  99.  laws  of  1907)  provides  that  hi 
sampling  cream  or  milk  from  which  composite  tests  are  to  be  made 
to  determine  the  per  cent  of  butter  fat  therein,  no  such  sampling 
shall  be  lawful,  unless  a  sample  be  taken  Irom  each  weighing,  and  the 
quantity  thus  used  shall  be  proportioned  to  the  total  weight  of  cream 
or  milk  tested. 

2  Kentucky   experiment   station.    Sth    report,    pp.    xxvl-xxvii. 


164  Testing  Milk  and  Its  Products. 

184.  If  the  diameter  of  the  sampling  pail  used  is  8 
inches,  and  that  of  the  sampling  tube  V2  inch,  the  quan- 
tity of  milk  secured  in  the  tube  will  always  stand  in  the 
ratio  to  that  of  the  milk  in  the  pail,  of  (i/2)2  to  82,1 
that  is,  as  1  to  256,  no  matter  how  much  or  how  little 
milk  there  is  in  the  pail,  the  sample  will  represent    _L 
part  of  the  milk.     For  composite  sampling  of  the  milk 
of  single  cows,  this  proportion  will  prove  about  ri^ht: 
if  more  milk  is  wanted  for  a  sub-sample,  dip  twice,  or 
pour  the  milk  to  be  sampled  into  a  can  of  smaller  diam- 
eter.    If  the  mixed  milk  from  a  number  of  cows  is  to 
be  sampled,  a  wider  sampling  can  may  be  used.     By  ad- 
justing the  diameter  of  the  tube  or  the  can.  any  de- 
sired proportion  of  milk  can  be  obtained  in  the  sample. 

For  factory  sampling,  with  a  weighing  can  26  inches 
in  diameter,  a  tube  three-quarters  of  an  inch  in  diameter 
will  be  found  of  proper  dimensions. 

In  using  these  tubes,  the  milk  or  cream  must  in  all 
cases  be  in  cylindrical  cans  when  the  sample  is  drawn. 

The  sampling  tube  will  furnish  a  correct  sample  of 
the  milk  in  the  can,  even  if  this  has  been  left  standing 
for  some  time;  it  is  better,  however,  to  take  out  the 
sample  soon  after  the  milk  has  been  poured  into  the  can, 
as  the  possible  error  of  cream  adhering  to  the  sides  of 
the  sampling  tube  is  then  avoided. 

185.  The  accuracy  of  the  sampling  of  milk  by  means 
of  the  Scovell  tube  was  proved  beyond  dispute  in  the 
breed  tests  conducted  at  the  World's  Columbian  Expo- 

1  The  contents  of  n  cylinder  are  represented  hy  the  formula  ^  r!h.  r 
being  the  radius  of  the  cylinder,  and  7?  Its  height.  The  relation  be- 
tween two  cylinders  of  the  same  height,  the  radii  of  which  are  It  and  r. 
Is  therefore  as  1J  K2h  to  r»h.  or  as  I{*  to  r2. 


Composite  Samples  of  Milk.  1U5 

sition  in  1893,  in  which  tests  this  method  was  adopted 
for  sampling  the  milk  produced  by  the  single  cows  and 
the  different  herds.1  The  data  obtained  in  these  breed 
tests  also  furnish  abundant  proof  of  the  accuracy  of  the 
Babcock  test. 

1 86.  Accuracy  of  the  described  methods  of  sam- 
pling. An  experiment  made  at  the  Wisconsin  Dairy 
School  may  here  be  cited,  showing  that  concordant  re- 
sults \\ill  be  obtained  by  the  use  of  the  drip  sampling 
method  and  the  Scovell  tube.  Two  composite  samples 
were  taken  from  fifty  different  lots  of  milk,  amounting 
to  about  6,000  Ibs.  in  the  aggregate.  One  sample  was 
taken  of  the  drip  from  a  hole  in  the  conductor  spout 
through  which  the  milk  passed  from  the  weighing  can; 
the  other  was  taken  from  the  weighing  can  by  means 
of  a  Scovell  sampling  tube.  The  following  percentages 
of  fat  were  found  in  each  of  these  samples  :2 


Babcock  test 

Gravimetric 
analysis 

Drip    e 
Scovell 

omposite   sample 

4.0   per  cent. 

4.0   per   cent. 

4.04  per  cent. 
4.06  per  cent. 

tube  composite  sample  

187.  d.  The  McKay  sampler  (fig.  53),  constructed  by 
Professor  (>.  L.  McKay,  formerly  of  I  own  experiment 
station,  consists  of  two  nickel-plated  brass  tubes  that 
telescope  one  within  the  other ;  both  have  a  milled 
slot  so  made  that  when  the  handles  stand  together  the 
slot  is  open ;  by  turning  the  handles  at  right  angles  the 

1  Kentucky  experiment  station,  8th  report,  pp.  xxx-xxxi.  Another 
form  of  a  milk  sampling  tube  in  use  at  the  Iowa  experiment  station 
was  described  and  illustrated  by  Mr.  Ei'kli  s  in  lireeder's  Gazt-tt-', 
May  19,  1897. 

1  See   also  199   et  siq. 


K;G 


Testing  Milk  and  Its  Products. 


slot  is  closed.  The  sampler  is  made 
in  two  lengths,  21  and  18  inches, 
and  has  been  found  very  convenient 
for  sampling  either  milk  or  cream. 
1873.  e.  Michels'  cream-sam- 
pling tube  consists  of  a  modified 
Scovell  sampler  in  a  tin  jacket.  It 
was  constructed  by  Professor  John 
Michels,  late  of  North  Carolina  agri- 
cultural college.  This  sampler  ren- 
ders possible  an  accurate  and  rapid 
sampling  of  any  cream,  regardless 
of  its  richness  and  acidity,  without 
stirring  the  cream. 

188.  f.  Composite  sampling  with  a 
"one-third  sample  pipette."  Milk  is 
PI°'  ?amp™re  McKa>'  sometimes  sampled  directly  from  the 
weighing  can  into  the  Babcock  test  bottle 
by  means  of  a  pipette  hold- 
ing 5.87  cc.,  which  is  one- 
third  the  size  of  the  regu- 
lar pipette.  This  quantity 
is  measured  into  the  test 
bottle  from  three  successive 
lots  of  milk  from  the  same 
patron  and  the  test  then 
made  in  the  ordinary  man- 
ner. In  this  way  one  test 
shows  the  average  composi- 
tion of  the  milk  delivered 
during  three  successive  days 
or  deliveries.  When  this 
method  is  adopted,  as  many 
test  bottles  are  provided  as 
there  are  patrons;  there  is  no 


Composite  Samples  of  MUk.    .  167 

need  of  using  any  preservatives  for  milk  in  this  case.  Fig.  55 
shows  a  convenient  rack  for  holding  the  test  bottles  used  in  com- 
posite sampling  with  a  "one-third  sample  pipette." 

Accurate  results  can  be  obtained  by  this  method  of  sampling, 
if  care  is  taken  in  measuring  out  the  milk,  and  if  it  is  not  frozen 
or  contains  lumps  of  cream.  It  is  doubtful  if  the  method  has  any 
advantage  over  the  usual  method  of  composite  sampling.  If  milk 
is  delivered  daily  and  each  lot  is  sampled  with  the  one-third 
pipette,  twice  or  three  times  the  number  of  tests  are  required  as 
when  composite  samples  are  taken  in  jars  and  tested  once  every 
week  or  ten  days.  This  method  furthermore  takes  a  little  more 
time  in  the  daily  sampling  than  the  other,  as  the  quantity  of  milk 
must  be  measured  out  accurately  each  time.  If  a  test  bottle  is 
accidently  broken  or  some  milk  spilled,  the  opportunity  of  ascer 
taining  the  fat  content  of  the  milk  delivered  during  the  three 
days  is  lost;  if  a  similar  accident  should  occur  in  testing  com- 
posite samples  collected  in  jars,  another  test  can  readily  be  made. 


PRESERVATIVES  FOR  COMPOSITE   SAMPLES. 

189.  When  milk  is  kept  for  any  length  of  time  under 
ordinary  conditions,  it  will  soon  turn  sour  and  become 
loppered,  and  further  decomposition  shortly  sets  in, 
which  renders  the  sampling  of  the  milk  both  difficult 
and  unsatisfactory  (19).  The  period  during  which  milk 
will  remain  in  an  apparently  sweet  or  fresh  condition 
varies  with  the  temperature  at  which  it  is  kept,  and 
with  the  cleanliness  <j>f  the  milk.  It  will  not  generally 
remain  sweet  longer  than  two  days  at  the  outside,  at 
ordinary  summer  or  room  temperature. 

In  order  to  preserve  composite  samples  of  milk  in  a 
proper  condition  for  testing,  some  chemical  which  will 
check  or  prevent  the  fermentation  of  the  milk  must  be 
added  to  it.  A  number  of  substances  have  been  pro- 
posed for  this  purpose. 


168  .  Testing  M.^lk  and  Its  Products. 

190.  Bi-chromate   of    potash.      This  preservative   is 
preferred  by  many   because  it  is  relatively  harmless, 
cheap  and  efficient.     The  bi-chromate  method  for  pre- 
serving samples  of  milk  was  proposed  by  Mr.  J.   A. 
Alen,   city  chemist  of  Gothenburg,  Sweden,  in  1892,1 
and  has  been  generally  adopted  in  dairy  regions  in  this 
country  and  abroad.     While  not  perfectly  harmless,  the 
bi-chromate  is  not  a  violent  poison  like  other  chemicals 
proposed  for  this  purpose,  and  no  accidents  are  liable 
to  result  from  its  use. 

191.  The  quantity  of  bi-chromate  necessary  for  pre- 
serving half  a  pint  to  a  pint  of  milk  for  a  period  of 
one  or  two  weeks   is  about  one-half   gram    (nearly   8 
grains),  about  one-half  as  much  as  can  be  placed  on  a 
dime. 

According  to  Winton  and  Ogden,2  a  .22-inch  pistol 
cartridge  shell  %  inch  long,  or  a  .32-inch  caliber  shell 
i/4  inch  long,  when  loosely  filled,  will  hold  enough  pow- 
dered bi-chromate  to  preserve  y2  pint,  and  a  .32-inch 
caliber  shell  %  ineh  long  will  h°ld  enough  to  preserve 
one  pint.  These  shells  may  be  conveniently  handled 
by  soldering  to  them  a  piece  of  stiff  wire  which  serves 
as  a  handle.  The  amount  of  bi-chromate  placed  in 
each  composite  sample  jar  would  fill  about  half  the 
space  representing  one  per  cent,  in  the  neck  of  a  Bab- 
cock  milk  test  bottle. 

192.  The  first  portions  of  milk  added  to  the  com- 
posite sample  jars  containing  the  specified  amount  of 
bi-chromate  will  be  colored   almost  red,   but  as  more 

1  Biedermann's  Centralblatt,    1892,  p.  549. 

"Connecticut  experiment   station,    report   for   1884,    p.    222 


Composite  Samples  of  Milk.  169 

milk  is  added  day  by  day,  its  color  will  become  lighter 
yellow.  The  complete  sample  should  have  a  light  straw 
color;  such  samples  are  most  easily  mixed  with  acid 
when  tested.  If  more  bi-chromate  is  used,  the  solution 
of  the  casein  in  the  acid  is  rendered  difficult  and  re- 
quires persistent  shaking.  Bi-chromate  can  be  bought 
at  drug  stores  or  from  dairy  supply  dealers  at  about  30 
cents  a  pound.  Powdered  bi-chromate  of  potash  should 
be  ordered,  and  not  crystals,  as  the  latter  dissolve  only 
slowly  in  the  milk.  Bi-chromate  tablets  containing  the 
correct  quantity  of  preservative  for  a  quart  or  pint  sam- 
ple have  also  been  placed  on  the  market  and  will  be 
found  convenient. 

193.  Corrosive  sublimate  tablets  for  composite 
samples.  During  late  years  corrosive  sublimate  tablets 
have  come  into  general  use  in  factories.  These  contain 
mercuric  chlorid  with  anilin  color  (rosanilin).1  The 
coloring  matter  is  added  to  give  a  rose  color  to  the  sam- 
ple preserved,  thus  showing  that  the  milk  is  not  fit  for 
consumption;  the  bi-chromate  giving  naturally  a  yellow 
color  to  the  milk,  renders  unnecessary  the  addition  of 
any  special  coloring  matter. 

Compounds  containing  corrosive  sublimate  are  violent 
poisons  and  must  always  be  handled  with  the  greatest 
care,  lest  they  get  into  the  hands  of  children  or  persons 
not  familiar  with  their  poisonous  properties;  they  will 
preserve  the  milk  longer  than  bi-chromate  when  applied 
in  sufficient  quantities. 

Among  other  substances  recommended  for  use  in  but- 
ter or  cheese  factories  as  milk  preservatives  for  com- 

1lrn-a   experiment   station,    bulletins   9,    11,   32. 


170  Testing  Milk  and  Its  Products. 

posite  samples  may  be  mentioned  formaldehyde,  boracic- 
acid  compounds,  chloroform,  carbon  bi-sulfid,1  copper 
ammonium  sulfate,  sodium  fluorid  and  ammonia  glycerin 
(sp.  gr.,  1.031). 

194.  Care  of  composite  samples.  The  composite 
sample  jars  should  be  kept  covered  to  prevent  loss  by 
evaporation,  and  in  a  cool,  dark  place,  or  at  least  out 
of  direct  sunlight  when  bi-chromate  of  potash  is  used 
as  a  preservative ;  the  chromic  acid  formed  by  the  re- 
ducing influence  of  light  on  chromate  solutions  pro- 
duces a  leathery  cream  which  it  is  difficult  to  dissolve  in 
sulfuric  acid. 

A  coating  of  white  shellac  has  been  suggested  to  pro- 
tect the  labels  of  the  composite  sample  jars.  The  shel- 
lac is  applied  after  the  names  of  the  patrons  have  been 
written  on  the  labels,  and  when  these  have  been  put  on 
the  jars.  Gummed  labels,  Ix2i^>  inches,  answer  this 
purpose  well. 

Numbers  are  sometimes  ground  on  the  sample  jar  or 
stamped  on  brass  tags  attached  to  the  jars  by  a  wire. 

In  keeping  the  milk  from  day  to  day,  care  should  be 
taken  that  the  cream  forming  on  the  milk  does  not  stick 
to  the  sides  of  the  jars  in  patches  above  the  level  of  the 
milk.  Unless  the  daily  handling  of  the  jars  and  the 
addition  of  fresh  portions  of  milk  be  done  carefully, 
the  cream  will  become  lumpy  and  will  dry  on  the  sides 
of  the  jars.  In  some  cases  it  is  nearly  impossible  to 
evenly  distribute  this  dried  cream  through  the  entire 
sample  at  testing  time  so  as  to  make  the  composite 

1  Delaware  experiment  station,  eighth  report,  1896,  vrhich  also  see  for 
trials  with  a  large  number  of  different  preservatives. 


Composite  Samples  of  Milk.  171 

sample  a  true  representative  of  the  different  lots  of  milk 
from  which  it  has  been  taken. 

195.  Every  time  a  new  portion  of  milk  is  added  to 
the  jar  this  should  be  given  a  gentle  horizontal  rotary 
motion,  thereby   mixing  the   cream  already  formed  in 
the  jar  with  the  milk  and  loosening  the  cream  stick- 
ing to  its  side.     This   manipulation  also  prevents  the 
surface  of  the  milk  from  becoming  covered  with  a  layer 
of  partially  dried  leathery  cream. 

Composite  samples  having  patches  of  dried  cream  on 
the  inside  of  the  jar  are  the  result  of  carelessness  or 
ignorance  on  the  part  of  the  operator.  If  proper  at- 
tention is  given  to  the  daily  handling  of  the  composite 
samples,  the  cream  formed  in  the  jars  can  again  be 
evenly  mixed  with  the  milk  without  difficulty. 

196.  Fallacy  of  averaging  percentages.  A  composite 
sample   of   milk  should  represent  the1  average  quality 
of  the  various  lots  of  milk  of  which  it  is  made  up.   This 
will  be  true  if  a  definite  aliquot  portion  or  fraction  of 
the  different  lots  of  milk  is  taken.     If  the  weights  of, 
say  ten  different  lots  of  milk,  are  added  together  and 
the  sum  divided  by  ten,  the  quotient  will  represent  the 
average  weight  per  lot  of  milk,  but  an  average  of  the 
tests  of  the  different  lots  obtained  in  this  way  may  not 
be  the  correct  average  test  of  the  entire  quantity  of 
milk.     The  accuracy  of  such  an  average  figure  will  de- 
pend on  the  uniformity  in  the  composition  and  weights 
of  the  ten  lots  of  milk.     When  there  is  no  uniformity, 
the  weights  of  the  different  lots  of  milk  as  well  as  their 
tests  must  be  considered.     The  following  example  will 
illustrate  the  difference  between  the  arithmetical  aver- 


172 


Testing  Milk  and  Its  Products. 


age  of  a  number  of  single  tests  and  the  true  average  test 
of  the  various  lots. 

Methods  of  calculating  average  percentages. 


I.    Mil) 

s  varying 
and  test 

in  weights 
i 

• 

II.    Mil 

k  of  unifo 
and  tests 

rm  weight 

s 

Lot 

ij 

i! 

jj 

Lot 

I! 

1* 

|3 

£  = 

I 

Ibs. 
120 

per  ct. 
5 

Ibs. 
4  2 

I 

Ibs. 
250 

per  ct. 
4  2 

Ibs. 
10  5 

II... 

570 

5.0 

28.5 

II... 

225 

4.0 

9.0 

Ill 

360 

•    18.7 

Ill 

240 

4.3 

10.3 

IV 

55 

3  0 

1  6 

IV 

238 

4  1 

9  7 

V... 

82 

4.0 

3.2 

V  

234 

4.4 

10.3 

Total  

1187 

56.2 

Total  

1187 

49.8 

'  Average  

True  average 
test 

237 

4.14 
4.73* 

11.24 

Average  

True  average 
test 

237 

4.20 
4  22 

10.0 

'56.2X100     .,, 

1187      =473  1187       -*-" 

197.  The  figures  given  in  the  table  show  that  when 
the  different  lots  of  milk  vary  in  test  and  weight,  as  in 
the  first  case,  the  correct  average  test  of  the  1187  Ibs. 
of  milk  is  not  found  by  dividing  the  sum  of  these  tests 
by  five,  which  would  give  4.14  per  cent. ;  but  by  divid- 
ing 56.2  (the  total  amount  of  fat  in  the  mixed  milk) 
by  1187  (the  total  amount  of  milk),  which  is  4.73; 
this  is  the  correct  average  test  of  the  mixed  milk  made 
up  of  the  five  different  lots. 

In  the  second  case,  the  variations  in  both  the  weights 
of  the  different  lots  of  milk  and  their  tests,  are  com- 
paratively small,  and  both  methods  of  calculation  give 
therefore  practically  the  same  average  test;  but  also  in 
this  case,  the  correct  average  test  is  found  by  dividing 


Composite  Samples  of  Milk.  173 

the  total  amount  of  fat  by  the  total  quantity  of  milk, 
making  4.22  per  cent,  instead  of  4.20  per  cent.,  which  is 
the  arithmetical  mean  of  the  five  tests.  The  quantities 
of  milk  in  the  various  lots  do  not  enter  into  the  calcula- 
tion of  the  latter.1 

198.  The  second    example    represents    more    nearly 
than   the  first  one  the  actual  conditions  met  with   at 
creameries  and  cheese  factories.     As  a  rule,  the  mixed 
milk  from  a  herd  of  cows  does  not  vary  more  in  total 
weight  or  tests,  within  a  short  period  of  time  like  one 
to  two  weeks,  than  the  figures  given  in  this  example. 
On  account  of  this  fact,  samples  taken,  for  instance, 
with  a  small  dipper  may  give  satisfactory  results  to  all 
parties  concerned.     If  the  different  lots  of  milk  varied 
in  weight  and  test  from  day  to  day,  as  shown  in  the 
first  case,  it  would  be  necessary  to  use  a  "milk  thief"  or 
one   of   the   sampling   tubes   for   taking  the   composite 
samples;  the  size  of  each  of  the  samples  taken  would 
then  represent  an  exact  aliquot  portion  of  the  various 
lots  of  milk  (182). 

199.  A  patron's  dilemma.     The   following  incident  will  fur- 
ther explain  the  difficulties  met  with  in  calculating  average  tests 
of  different  lots  of  milk. 

The  weekly  composite  sample  of  the  milk  supplied  by  a  cream- 
ery patron  from  his  herd  of  21  cows  tested  4.0  per  cent.  fat. 
One  day  the  farmer  brought  to  the  creamery  a  sample  of  the 
morning's  milk  from  each  of  his  cows,  and  had  them  tested; 
after  adding  the  tests  together  and  dividing  the  sum  by  21,  he 
obtained  an  average  figure  of  5.1  per  cent,  of  fat.  From  this 
he  concluded  that  the  average  test  of  the  milk  from  his  cows 


1  In  the  experiment  srivcn  <>n  p.  14S,  the  arithmetical  mean  of  the 
tests  is  5.15  per  cent.,  wliilp  the  true  average  fat  content  of  milk 
is  4.85  per  cent. 


174  Testing  Milk  and  Its  Products. 

ought  to  be  5.1,  instead  of  4.0,  and  naturally  asked  for  an  ex- 
planation. 

The  first  thing  done  vras  to  show  him  that  while  5.1  was  the 
correct  average  of  the  figures  representing  the  tests  of  his 
twenty-one  cows,  it  was  not  a  correct  average  test  of  the  mixed 
milk  from  all  his  cows,  as  he  had  not  considered,  in  calculating 
this  average,  the  quantities  of  milk  yielded  by  each  cow;  the 
following  illustration  was  used: 

Cow  No.  1,  yield  25  Ibs.  of  milk,  test  3.6  per  cent,  =0.9  Ib.  of  butter  fat. 
Cow  No.  2,  yield    6  Ibs.  of  milk,  test  5.0  per  cent,  =0.3  Ib.  of  butter  fat. 

Total 31  Ibs.  2)8.6  1.2  Ibs. 

4.3  per  cent 

The  two  cows  gave  31  Ibs.  of  milk  containing  1.2  Ibs.  of  fat; 
the  test  of  the  mixed  milk  would  therefore  not  be  4.3  per  cent. 

/3.6+5.0\     but  1.2X100  _ g  8?  ccnt        ,f    fhe    fat    jn    the    mixe(, 

\        2        /  31 

milk  was  calculated  by  the  average  figure  4.3  per  cent.,  1.33  Ibs. 
of  fat  would  be  obtained,  i.  e.,  0.13  Ib.  more  than  the  cows  pro- 
duced. 

In  order  to  further  demonstrate  the  actual  composition  of  the 
mixed  milk  of  the  twenty-one  cows,  the  milk  of  each  cow  was 
weighed  and  tested  at  each  of  the  two  milkings  of  one  day.  The 
weights  and  tests  showed  that  the  cows  produced  the  following 
total  number  of  pounds  of  milk  and  of  fat: 

Morning  milking,  113.3  Ibs.  of  milk,  containing  5.17  Ibs.  of  fat. 

Night  milking,       130.9  Ibs.  of  milk,  containing  4.98  Ibs.  of  fat. 

The  morning  milk  therefore  contained  5-^^°°  =4.56  per  cent, 
of  fat,  and  the  night  milk,  4-^°°  =3.80  per  cent,  of -fat. 

The  sum  of  the  morning  and  night  milkings  gave:  milk,  244.2 
Ibs.,  fat  10.15  Ibs.  The  mixed  morning  and  night  milk,  there 
fore,  contained  10'2^X2100  ^-4.1  per  cent,  of  fat.  This  is  the  true 
average  test  of  the  morning  and  night  milkings  of  these  twenty- 
one  cows,  as  found  by  weighing  and  testing  separately  the  milk 
of  each  cow  at  both  milkings. 

The  total  milk  was  strained  into  a  large  cav  at  the  farm,  both 
in  the  morning  and  in  the  evening.  A  sample  ^f  the  mixed  milk 
was  in  each  case  taken  with  a  long-handled  dipper  as  soon  as 
the  milkings  were  finished.  "When  the  cans  of  milk  were  deliv- 


Composite  Samples  of  Milk. 


175 


ered  at  the  creamery;  a  sample  of  each  was  taken  with  a  Scovell 
sampling  tube.  The  tests  of  these  four  samples  are  given  below, 
together  with  the  results  of  the  individual  tests: 


Morning  Milk 

Night  Milk 

Sample  taken  at  the  farm,  with  dip- 
per- 

4.4  per  cent. 

3.8  per  cent 

Sample  taken  at  creamery  with  Sco- 
vell tube  _  

4.5         " 

3.7         " 

Calculated  from  weights  and  tests  of 
milk  from  each  cow 

4.5         '  ' 

3.8         " 

• 

The  figures  given  show  that  practically  uniform  tests  were  ob 
fained  by  the  different  methods  of  sampling. 


Questions. 

1.  What  is  a  composite  sample  of  milkt 

2.  Describe  the  proper  care  of  composite  samples. 

3.  Give  an  example  showing  that  composite  samples  of  milk 
may  be  inaccurate  when   taken  with  a  small   dipper. 

4.  Describe  the  following  methods  of  sampling  milk  or 
cream,  by  (a)  drip  sample,  (b)  the  Scovell,  (c)  the  McKay, 
and  (d)  the  Michels'  sampling  tubes. 

5.  What  is  the  purpose  of  adding  preservatives  to  milk  or 
cream  samples  f  Mention  the  more  common  preservatives  usetl 
and  quantities  to  be  added. 


CHAPTER  XL 
CREAM  TESTING  AT  CREAMERIES. 

200.  The  cream  delivered  at  gathered-cream  factories 
is  now  tested  by  the  Babcock  test  in  many  localities,  and 
this  has  been  adopted  as  a  basis  of  paying  for  the  cream 
in  the  same  manner  as  milk  is  paid  for  at  separator 
creameries,  except  that  tests  are  made  of  each  lot  of 
cream  and  -not  of  composite  samples.     This  method  has 
now  largely  replaced  those  formerly  used  for  this  pur- 
pose, such  as  the  oil -test  churn  or  the  space  (or  gauge) 
system. 

The  details  of  the  application  of  the  Babcock  test  to 
the  practical  work  at  cream-gathering  creameries  have 
been  carefully  investigated  by  Winton  and  Ogden,1 
Bartlett,2  Lindsay,3  and  Hunziker.4 

201.  The  space  system.     The  space  is  the  volume  of 
a  cylinder,  8V>  inches  in  diameter  and    10    of  an  inch 

,     '  64 

high.  The  number' of  spaces  in  each  can  of  milk  is  read 
off  before  skimming  by  means  of  a  scale  marked  on  a 
strip  of  glass  in  the  side  of  the  can.  Numerous  tests 
have  shown  that  one  space  or  gauge  of  cream  does  not 
contain  a  definite,  uniform  amount  of  fat.  In  over  100 
comparisons  made  by  "Winton  it  was  found  that  one 
space  of  cream5  contained  from  .072  to  .170  Ib.  of  butter 

'Conn,  exprrtment  station  (New  Haven),  bull.  108  and  11!);  report 
l?94,  pp.  214-244. 

*  Maine   experiment    station,   bull.    3    and    4    (S.    S.) 

*  Ilntch  experiment  station,  report  1894,  pp.  02-103:  1805,  pp.  67-70. 
4  Indiana  experiment  station,  cir.  42. 

6  Conn.  exp.  sta..  bull.  119. 


Cream  Testing  at  Creameries. 


177 


fat,  or  on  the  average  .13  lb.,  and  the  number  of  spaces 
required  to  make  one  pound  of  butter  varied  from  5.01 
to  11.72.  It  is  also  claimed  that  in  the  winter  season 
when  cream  is  gathered  at  long  intervals,  like  once  a 
week,  it  is  necessary  for  the  buyer  to  accept  the  seller's 
statement  of  the  record  of  the  number  of  cream  spaces 
which  he  furnishes,  since  the  cream  cannot  be  left  in 
the  creaming  can  for  so  long  a  time.  These  objections  to 
the  space  system  apply  only  to  the  method  of  paying 
for  the  cream,  and  not  to  the  manner  in  which  the 
cream  is  obtained. 

202.  The  oil-test  churn.  As  stated  in  the  introduc- 
tion, the  oil -test  churn  (fig.  56)  was  formerly  used  quite 
extensively  a  m  o  n-g 
gathered-cream  fac- 
tories ;  this  system  is 
based  on  the  number 
of  inches  of  cream 
which  the  various  pa- 
trons deliver  to  the 
factory;  a  creamery 
inch  is  the  quantity  of 
cream  which  will  fill 
a  can  twelve  inches 
wide,  one  inch  high ; 
it  contains  113  cubic 
inches.1  This  quantity 
pound  of  butter. 

In  using  this  method  the  driver  pours  the  patron's 
cream  into  his  12-inch  gathering  pail,  measures  it  with 

'A   layer  of   two  inches   in   an    8-inch   pail   contains   100.531   cubic 
inches,    two   inches   in   a   8%-inch   pail   110.18   cubic  Inches,   and   two 
inches  in  n  8%-inch  pail  113.49  cubic  inches. 
12 


FIG.  56.     The  oil-test  churn. 


was    supposed    to  make   one 


178 


Testing  Milk  and  Its  Products. 


his  rule  and  records  the  depth  of  the  cream  in  the  can. 
in  inches  and  tenths  of  an  inch.  The  cream  is  then 
stirred  thoroughly  with  a  ladle  or  a  stout  dipper,  and 
sampled  by  filling  a  test  tube  to  the  graduation  mark 
by  means  of  a  small  conical  dipper  provided  with  a 
lip.  A  driver's  case  contains  either  two  or  three 
"cards,"  holding  fifteen  test  tubes  each  (see  fig.  57) 

The  tubes  as  filled  are 
placed  in  the  case  and 
the  corresponding  num- 
ber in  each  instance  re- 
corded in  front  of  the 
patron's  name,  together 
with  the  number  of 
inches  of  cream  fur- 
nished by  him. 

On  the  arrival  at  the 
creamery  the  tin  cards 
holding  the  tubes  are  placed  in  a  vessel  filled  with 
water  of  the  churning  temperature  (say,  60°  in  summer 
and  65°  to  70°  in  winter).  When  ready  for  churning 
they  are  placed  in  the  oil-test  churn  (fig.  56),  the  cover 
of  the  churn  put  on,  and  the  samples  of  cream  churned 
to  butter.  On  the  completion  of  the  churning,  the  cards 
are  transferred  to  water  of  175-190°  Fahr.,  where  they 
are  left  for  at  least  ten  minutes  to  melt  the  butter  and 
"cook  the  butter  milk  into  a  curd."  'The  oil 'will  now 
be  seen  mixing  through  the  mass.  The  test  tubes  are 
then  cooled  to  churning  temperature  and  churned 
again,  by  which  process  the  curd  is  broken  into  fine 


FIG.  57.     Cream-gatherer's 
sample  case. 


Cream   Testing  at  Creameries.  179 

particles,  which,  when  the  butter  is  re-melted,  will  set- 
tle to  the  bottom.  The  butter  is  melted  after  the  sec- 
ond churning  by  placing  the  tubes  in  water  at  150-175° 
F.,  allowing  them  to  remain  therein  for  at  least  twenty 
minutes.  Some  samples  must  be  churned  three  or  four 
times  before  a  good  separation  of  oil  is  obtained.  A 
clear  separation  of  oil  is  often  facilitated  by  adding  a 
little  sulfuric  acid  to  the  tubes. 

The  length  of  the  column  of  liquid  butter  fat  is  de- 
termined by  means  of  a  special  rule  for  measuring  the 
butter  oil ;  this  rule  shows  the  number  of  pounds  and 
tenths  of  a  pound  of  butter  which  an  inch  of  cream  will 
make;  the  first  tenth  of  a  pound  on  the  rule  is  divided 
into  five  equal  parts,  so  that  measurements  may  be  made 
to  two-hundredths  of  a  pound.  The  melted  fat  is  meas- 
ured with  the  rule,  by  raising  the  tin  card  holding  the 
bottles  to  about  the  height  of  the  eye;  the  reading  is 
recorded  on  the  driver's  tablet  under  Test  per  inch,  op- 
posite the  number  of  the  particular  patron.  The  test 
multiplied  by  the  inches  and  tenths  of  an  inch  of  cream 
supplied  will  give  the  amount  of  butter  in  pounds,  with 
which  the  patron  will  be  credited  en  the  books  of  the 
creamery. 

203.  The  objection  to  this  system  of  ascertaining  the 
quality  of  cream  delivered  by  different  patrons  lies  in 
the  fact  that  it  determines  the  churnable  fat,  and  not 
the  total  fat  of  the  cream;  the  amount  of  the  former 
obtained  depends  on  many  conditions  beyond  the  con- 
trol of  the  patron,  viz.,  the  consistency,  acidity  and  tem- 
perature of  the  cream,  the  size  of  the  churn  or  churn- 


180  Testing  Milk  and  Its  Products. 

ing  .vessel,  etc.1  The  same  reasons  which  caused  the 
churn  to  be  replaced  by  methods  of  determining  the 
total  fat  of  the  milk,  in  the  testing  of  cows  among  dairy- 
men and  breeders,  have  gradually  brought  about  the 
abandonment  of  the  oil  test  in  creameries  and  the  adop- 
tion of  the  Babcock  test  in  its  place. 

204.  The  Babcock  test  for  cream.  Both  the  space 
system  and  the  oil-test  churn  used  for  estimating  the 
quality  of  cream  at  creameries  have  now  largely 
been  replaced  by  the  Babcock  test  in  the  creameries 
in  this  country.  On  account  of  the  great  varia- 
tion in  both  the  richness  and  the  acidity  of  farm 
separator  cream  it  has  been  found  in  practice  that  com- 
posite samples  of  cream  are  not  so  satisfactory  to  either 
buyer  or  seller  as  the  testing  of  a  sample  taken  from 
each  lot  of  cream  gathered. 

The  following  method  of  collecting  and  sampling 
cream  is  now  commonly  used  by  creameries.  The  cream 
gatherer  who  collects  the  cream  in  large  cream  cans  is 
supplied  with  a  spring  balance  (1,  see  fig.  58),  a  pail  for* 
sampling  and  weighing  the  cream  (2),  sampling  tube 
(3),  collecting  bottles  (5),  and  a  record  book.  At  each 
patron's  farm  he  takes  from  his  wagon  the  sampling 
pail  and  tube,  the  scales,  and  one  small  collecting 
bottle.  He  should  find  in  the  dairy  of  the  patron  the 
cans  of  perfectly  sweet  cream,  kept  at  a  temparature 
of  40  to  50  degree  F.,  and  protected  from  dirt  and  bad 

a  It  follows  from  this  that  there  can  be  no  definite  relation  between 
the  results  obtained  by  the  Babcock  test  and  the  oil-test  readings ; 
a  reading  of  100  in  the  oil-test  is.  however,  on  the  average,  equivalent 
to  about  23  per  cent,  of  butter  fat  in  the  cream. 


Testing  Cream  at  Creameries. 


181 


odors.  The  gatherer 
hangs  the  scale  on  a  hook 
near  the  cream  to  be  col- 
lected; the  scale  should  be 
made  so  that  the  hand  of 
the  dial  will  stand  at  zero 
when  the  empty  pail  is 
hung  on  it.  The  cream  is 
then  poured  at  least  twice 
from  one  can  to  another 
in  order  to  mix  it 
thoroughly.1 


FIG.  58.     Outfit  for  cream  testing 
jred- 
cream  factories. 


by    the    Babcock    test    at    gather 


205.  Thin,  sweet  cream  is 
comparatively  easy  to  mix,  either 
by  pouring  or  by  using  a  tin  stir- 
rer  attached  to  an  iron  rod  about, 
two  feet  long.  Many  lots  of 
cream,  however,  are  thick  and 
sour  when  the  cream  gatherer  col- 
lects them,  and  satisfactory 
weigh-  samples  can  only  be  obtained  by 
repeated  mixing  by  pouring;  in 
some  cases  it  is  necessary  to  warm  the  cream  and  even 
to  pour  it  through  a  strainer  to  get  a  uniform  mixture. 

'The  necessity  of  care  in  mixing  the  cream  is  shown  by  the  follow- 
ing illustration  given  by  the  authors  referred  to. 

Percent  of  /at  in  cream  which  stood  for  24  hours. 

Sample  drawn 


FIG.  58a.     Crear 
ing  pail. 


Surface.  Bottom. 

Not    mixed 28.00  5.00 

Poured     once 23.75  22.00 

roured     twice 


with  sampling  tube. 
19.25 
22.50 
22.25 


182 


Testing  Milk  and  Its  Products. 


J8b.       Cream    sample 
bottles. 


After  mixing  as  well 
as  possible,  each  lot  of  cream 
is  poured  into  the  cream- 

f(l     A  I  weighing     pail     (Fig.    58a), 

from  which  a  sample  for 
testing  is  taken  by  means  of 
a  sampling  tube  of  about 
one-half  inch  diameter.  This 
tube  is  emptied  into  a  num- 
bered bottle  (Fig.  58b)  in 

which  the  cream  is  kept  Until  tested.  The  weighing 
pail  is  sometimes  cleaned  after  emptying,  by  using  a 
rubber  scraper  and  the  tube  must  be  completely  drain- 
ed and  cleaned  before  another  lot  of  cream  is  sampled. 
A  combined  stirrer  and  sampler  is  sometimes  used  in- 
stead of  the  sampling  tube. 

206.  Tne  samples  of  cream  in  the  small  bottles,  be- 
sides furnishing  the  means  of  testing  the  richness  of  the 
cream,  give  the  creamery  man  an  opportunity  to  in- 
spect the  flavor  of  each  lot  of  cream,  and  the  condition 
in  which  this  has  been  kept  by  the  various  patrons.  If 
the  cream  samples  are  tested  soon  after  being  collected 
no  preservative  is  needed  and  the  cream  left  after  fil- 
ling the  test  bottles  may  be  saved,  but  if  the  samples 
must  be  kept  sometime  before  testing,  a  small  quantity 
of  some  preservative  (193)  should  be  added  to  the 
samples  to  keep  them  in  as  good  condition  as  possible 
until  they  are  tested. 


Testing  Cream  at  Creameries.  18^ 

The  samples  are  tested  by  weighing  either  9  or 
]  8  grams  of  the  carefully  mixed  sample  into  cream-test 
bottles,  as  explained  in  chapter  IV  (91). 

207.  The  collecting  bottles  should  be  cleaned  with 
cold,  and  afterwards  with  hot  water,  as  soon  as  they  are 
emptied,  and  before  a  film  of  cream  dries  on  them. 
When  washed  and  dried,  these  bottles  are  placed  in  the 
cases,  ready  for  the  next  collecting  trip. 


FIG.  58c.      Cream  sample  bottle  case. 

208.  When  this  system  of  Vesting  cream  samples 
is  adopted,  the  patrons  are  paid  for  the  number  of 
pounds  of  butter  fat  contained  in  their  cream,  in 
the  same  way  as  milk  is  paid  for  at  separator 
creameries.  It  makes  no  difference  how  thick  or  how 
thin  the  cream  may  be,  or  how  much  skim  milk  is  left 
in  the  cream  when  brought  to  the  factory.  Eighty 
pounds  of  cream  containing  15  per  cent,  of  fat  is  worth 
no  more  nor  less  than  48  pounds  of  cream  testing  25  per 
cent. ;  in  either  case  12  pounds  of  pure  butter  fat  is 
delivered.  This  will  make  the  same  amount  of  butter 
in  either  case,  viz.,  about  14  Ibs.,  and  both  patrons 
should  therefore  receive  the  same  amount  of  money. 


184  Testing  Cream  and  Its  Products. 

There  is  a  small  difference -in  the  value  of  the  two 
lots  of  cream  to  the  creamery  owner  or  the  butter  maker, 
in  favor  of  the  richer  cream,  both  because  its  smaller 
bulk  makes  the  transportation  and  handling  expenses 
lighter,  and  because  slightly  less  butter  fat  will  be  lost 
in  the  butter  milk,  a  smaller  quantity  of  this  being  ob- 
tained from  the  richer  cream. 

209.  Small  differences  in  the  composition  of  cream 
will,  however,  always  occur,  even  if  the  same  system  of 
creaming  the  milk,  like  the  centrifugal  process,  is  used 
and  all  factors  remain  as  nearly  the  same  as  possible  at 
all  times.  This  is  due  to  differences  in  the  composition 
of  the  milk  and  its  creaming  quality;  whether  largely 
from  fresh  cows  or  from  late  milkers;  whether  kept 
standing  for  a  time  before  being  set,  or  submerged  in 
the  creamer  immediately  after  milking  and  straining, 
diameter  of  creaming  cans,  etc.  Bartlett  states1  that 
the  percentage  of  fat  in  the  cream  from  the  same  cows 
may  be  increased  ten  per  cent,  or  more  by  keeping  the 
water  at  70°  instead  of  at  40°  F.  The  higher  tempera- 
ture will  give  the  richer  cream,  but  the  separation  will 
not  be  so  complete,  since  a  richer  skim  milk  is  obtained 
from  the  milk  set  at  this  temperature. 

Separator  cream  is  not  materially  influenced  by  the 
conditions  mentioned,  but  even  though  the  separator 
can  be  regulated  to  deliver  cream  of  nearly  uniform 
richness  from  all  kinds  of  sweet  milk,  considerably  var- 

1Bull.    3  (S.    S.),    Maine    experiment    station. 


Testing  Cream  at  Creameries.  185 

iatidns  in  the  richnes  of  the  cream  from  the  same  farm 
may  occur  because  of  variations :  1,  in  the  speed  of 
the  separator  bowl;  2,  the  temperature  of  the  milk;  3, 
the  rate  of  the  flow  of  milk  into  the  separator  bowl, 
and  4,  the  amount  of  water  or  skim  milk  used  to  flush 
out  the  bowl  when  through  skimming. 

210.  At  creameries  where  both  milk  and  cream  are 
delivered,  somewhat  of  an  injustice  is  done  to  patrons  de- 
livering cream,  by  paying  for  the  amounts  of  butter  fat 
furnished    by   the   different   patrons,    since    the   milk 
patron  receives  pay  for  all  the  fat  in  the  milk  including 
that  in  the  skim  milk.     By  multiplying  the  cream  fat 
by  1.03,2  the  value  of  his  products  to  the  creamery  is 
taken  into  proper  account,  and  justice  is  done  to  all 
parties  concerned3  (239). 

211.  Gathering      and      sampling      hand-separator 
cream.     A  still  more  satisfactory  method  is  to  provide 
separate  cans  for  each  patron,  the  cream  gatherer  leav- 
ing an  empty,  clean  can  at  each  farm  and  taking  a  full 
or  partially  filled  can  of  cream  from  the  farm  to  the 
factory.     This  makes  it  necessary  for  the  cream  gath- 
erer to  carry  as  many  cans  as  he  has  patrons  to  gather 
cream  from,  but  it  gives  the  factory  operator  a  chance 
to  inspect,  weigh  and  sample  the  cream  from  each  farm 


*  Spillman    (Dairy    and    Creamery,    Chicago,    April    1, 
mends  the  use  of  the  factor  1.044. 

•This  subject  is  discussed  in  detail  in  the  17th  annual  report  of  Wis. 
experiment  station,  pp.  90-92  ;  see  also  the  20tb  report  of  that  Station, 
pp.  130-31. 


186  Testing  Milk  and  Its  Products. 

and  relieves  the  cream  gatherer  of  all  these  details 
are  often  the  cause  of  dissatisfaction. 


Questions. 

1.  In  what  ways  do  .the  results  obtained  with  the  oil-test 
churn  differ  from  those  obtained  with  the  Babcock  testt 

'2.  Describe  the  method  of  testing  cream  by  the  Babcock  test 
nt  gathered-cream  factories. 

3.  What  advantages  has  the  gathering  of  cream  in  separate 
cans  over  mixing  the  cream  from  all  the  patrons  of  one  route* 


CHAPTER  XII. 
CALCULATION  OF  BUTTER-  AND  CHEESE  VIELD 

A. — CALCULATION  OF  YIELD  OF  BUTTER. 

212.  Butter-fat  test  and  yield  of  butter.  The  Bab- 
cock  test  shows  the  amount  of  pure  butter  fat  contained 
in  a  sample  of  milk,  cream  or  other  dairy  products. 
The  butter  obtained  by  churning  cream  or  milk  con- 
tains, in  addition  to  butter  fat,  a  certain  amount  of 
water,  salt  and  curd.  While  an  accurate  milk  test 
gives  the  total  quantity  of  butter  fat  found  in  the  sam- 
ple of  milk  or  cream  tested,  the  churn  cannot  be  de- 
pended upon  either  to  leave  the  same  amount  of  butter 
fat  in  the  butter  milk  or  to  include  the  same  amount  of 
water,  salt  or  curd  in  the  butter  at  each  churning. 

If  a  quantity  of  milk,  say  3,000  Ibs.,  be  thoroughly 
mixed  in  a  vat,  and  then  divided  into  half  a  dozen  equal 
portions,  a  Babcock  test  of  the  different  lots  will  show 
the  same  percentage  of  butter  fat  in  each  portion.  If, 
on  the  other  hand,  each  of  these  lots  be  skimmed,  and 
the  cream  ripened  in  different  vats  and  churned  sepa- 
rately, the  same  weight  of  butter  from  each  lot  of  500 
Ibs.  of  milk  will  not  be  obtained,  even  by  the  most  expert 
butter  maker,  or  if  all  the  operations  of  skimming,  cream 
ripening,  churning,  salting  and  butter-working  were 
made  as  nearly  uniform  as  possible.  Careful  operators 
can  handle  the  milk  and  cream  so  that  very  nearly  the 


188 


Testing  Milk  and  Its  Products. 


same  proportion  of  fat  contained  in  the  milk  is  re- 
covered in  the  butter  in  different  churnings,  but  since 
the  water  and  salt  in  butter  are  held  mechanically  and 
are  not  chemically  combined  with  it,  the  amounts  re- 
tained by  the  butter  are  quite  variable  in  different 
churnings. 

213.  Variations  in  the  composition  of  butter.  As 
an  illustration  of  the  variations  in  the  composition  of 
butter  that  usually  occur,  the  analyses  made  in  the 
breed  tests  at  the  World's  Fair  in  1893  may  be  here 
cited;  the  butter  was  in  all  cases  made  by  as  nearly 
identical  methods  and  under  as  uniform  conditions  as 
could  possibly  be  obtained  by  the  skilled  operators  hav- 
ing this  work  in  charge ;  the  average  composition  of  350 
samples  of  this  butter,  with  upper  and  lower  limits, 
was  as  shown  in  the  following  table: 

Composition  of  samples  of  butter,  World's  Fair,  1893. 


Sum  of 

Water 

Fat 

Curd 

Salt  and 

water,  curd, 

ash 

salt  and 

ash 

Average  of  350  analy- 

Per cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

ses  

11.57 

84.70 

.95 

2.78 

15.30 

Lower  and  upper  lim- 
its    

8.63-15.00 

76.53-88.26 

.50-2.14 

1  01-8  58 

Analyses  of  fifty  samples  of  creamery  butter  taken  in 
1896,  from  the  tubs  ready  for  market  at  as  many  Wis- 
consin creameries,  showed  that  no  two  of  them  were  ex- 
actly alike  in  composition,  but  varied  within  the  limits 
given  on  the  following  page  :* 


Wisconsin    experiment   station,   bul'.   5t5. 


Calculation  of  Butter-  and  Cheese  Yield.        189 
Summary  of  analyses  of  Wisconsin  creamery  butter. 


Sum  of 

Salt  and 

water,  curd, 

\Vater 

Fat 

Curd 

ash 

salt  and 
ash 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Highest 

17  03 

87  50 

2  45 

4  73 

22  95 

Lowest 

9.18 

77.07 

.36 

1.30 

12.50 

12.77 

88.03 

1.28 

2.87 

16.92 

The  preceding  analyses  shew  the  composition  of  but- 
ter made  at  one  place  where  every  possible  effort  was 
taken  to  produce  a  uniform  product,  and  of  butter  made 
at  fifty  different  creameries,  where  there  was  more  or 
less  variation  in  the  different  operations  of  manufacture 
and  in  the  appliances  and  machinery  used.  The  ma- 
jority of  the  samples  of  butter  analyzed,  in  either  case, 
were  very  near  the  average  composition  given,~but  since 
there  are  such  wide  variations  in  the  composition  of  the 
butter  made  by  the  uniform  methods  adopted  in  the 
World's  Fair  breed  tests,  butter  of  a  more  uniform  com- 
position cannot  be  expected  from  the  thousands  of  dif- 
ferent creameries  and  private  dairies  which  supply  the 
general  market  with  butter. 

The  analyses  of  the  fifty  samples  of  creamery  butter, 
given  above,  show  that  the  content  of  the  butter  fat 
varied  from  77  to  87.5  per  cent.,  and  according  to 
the  average  of  the  analyses,  83  pounds  of  butter  fat  was 
contained  in,  or  made,  100  Ibs.  of  butter.  There  was, 
therefore,  in  this  case  produced  20.5  per  cent,  more 
butter  than  there  was  butter  fat,  since 
83 : 100 :  :  100 :  x ;  therefore 

100X100 
x=  —          —  =120.a. 


190  Testing  Milk  and  Its  Products. 

214.  "Overrun"  of  churn  over  test.     The  yield  of 
butter  is  not,  however,  as  a  rule  compared  with  the 
amount  of  butter  fat  contained  in  the  butter,  but  with 
the  total  butter  fat  of  the  whole  milk  or  cream  from 
which  it  was  made.     This  "increase  of  the  churn  over 
the  test"  is  what  is  generally  called  overrun  in  cream- 
eries. 

The  overrun  obtained  in  different  creameries,  or  even 
in  the  same  creameries  at  different  times,  will  be  found 
to  vary  considerably.  When  the  milk  is  accurately 
tested  and  the  butter  well  worked,  this  overrun  will  vary 
from  10  to  16  per  cent. ;  that  is,  if  a  quantity  of  milk 
contains  exactly  100  Ibs  of  butter  fat,  as  found  by  the 
Babcock  test  or  any  other  accurate  method,  from  110  to 
116  Ibs.  of  butter  ready  for  market  will  be  obtained  from 
it.  The  overrun  from  cream  will  be  somewhat  larger, 
18  to  22  percent.,  but  will  never  exceed  25  percent.,  un- 
less the  butter  contains  less  than  80  per  cent,  fat  (217). 

215.  Factors   influencing   the   overrun   from     milk. 
Even  under  the  very  best  of  care  and  attention  to  de- 
tails, variations  will  occur  in  the  speed  of  the  separator, 
in  the  conduct  of  the  ripening  and  churning  processes, 
in   the  condition    of   the  butter    when     the    churn   is 
stopped ;    and   in  the  manner    of  working  the  butter ; 
hence     absolutely     uniform    losses    of   .fat    in    skim 
milk  and  butter  milk,  or  the  same  water-  and  salt  con- 
tents of  the  butter,  cannot  be  expected. 

The  overrun  in  separator  creameries  is  influenced  by 
two  legitimate  factors :  first,  the  losses  of  butter  fat  sus- 
tained in  separating  the  milk  and  churning  the  cream, 
and  second,  the  gain  due  to  the  admixture  of  water, 


Calculation  of  Butter-  and  Cheese  Yield.        191 

salt,  etc.,  in  the  manufacture  of  butter.  Considering 
first  the  losses  of  fat  in  skim  milk  and  butter  milk,  the 
separator  will  usually,  when  run  at  normal  speed  and 
capacity,  leave  the  same  per  cent,  of  fat  in  skim  milk, 
whether  rich  or  poor  milk  is  skimmed.  An  exception 
to  this  may  be  found  in  separating  rich  milk  having 
large  fat  globules,  or  milk  from  fresh  milkers,  in  either 
of  which  cases  the  large  size  of  the  fat  globules  occa- 
sions a  more  complete  separation  of  fat  by  the  centri- 
fugal force.  But  generally  speaking,  the  statement 
holds  good  that  the  total  loss  of  fat  in  separator  skim 
milk  is  a  factor  of  the  quantity  of  milk  run  through  the 
separator,  rather  than  of  its  quality. 

216.  The  losses  from  poor,  rich  and  average  milk,  as 
received  at  creameries  and  cheese  factories,  can  be  traced 
from  the  following  statement ;  this  gives  the  quantities 
of  fat  lost  in  handling  milk  of  four  grades,  viz.:  2.5, 
3.5,  4.0  and  6.0  per  cent.,  in  case  of  each  grade  calcu- 
lated to  a  standard  of  100  Ibs.  of  fat  in  the  milk. 

To  supply  100  Ibs.  of  fat  would  require  the  following 
amounts  of  the  different  grades  of  milk : 

4000  Ibs.  of  milk  testing  2.5  per  cent  will  contain  100  Ibs.  of  fat. 

2857           "      "          "35  "           "         "          100     "   "   " 

2500           «      «          «       4.0  "           "         "          100     "   "   " 

1666           "      "          "       6.0  "           "         "          100     "   "   " 

Assuming  that  the  skim  milk  contains  .1  per  cent,  of 
fat  and  makes  up  85  per  cent,  of  the  whole  milk,  and 
that  the  butter  milk  tests  .3  per  cent.,  and  forms  10 
per  cent,  of  the  whole  milk,  the  butter-fat  record  of 
the  quantities  of  different  grades  of  milk  containing  100 
Ibs.  of  fat  will  be  as  given  in  the  following  table.  Cer- 


192 


Testing  Milk  and  Its  Products. 


tain  mechanical  losses  are  unavoidable  in  the  cream- 
ery, as  in  all  other  factory  operations,  viz.,  milk  and 
cream  remaining  in  vats  and  separators,  butter  sticking 
to  the  walls  of  the  churn,  etc.  These  losses  have  been 
found  to  average  about  3  per  cent,  of  the  total  fat  in 
the  milk  handled,  under  normal  conditions  and  under 
good  management  (219). 

Fat  available  for  butter  in  different  grades  of  milk. 


Grade  of  milk 

Whole 
milk 

Skim 
milk 

Butter 
milk 

Waste 

Total 
loss 

Fat 
available 
forj 
[  butter 

2.5  per  cent  
Fat.  —  . 

4000  Ibs. 
2.5  per  ct. 

3400  Ibs. 
.1  per  ct. 

400  Ibs. 
.3  per  ct. 

Lbs. 
3.0 

Lbs. 
7.6 

Per_ct. 
92.4 

IOC  Ibs. 

3.4  Ibs. 

1.2  Ibs. 

3.5  per  cent  
Fat  

2857  Ibs. 
3.5  per  ct. 

2429  Ibe. 
.1  perxct. 

286  Ibs. 
.3  per  ct. 

3.0 

6.3 

93.7 

100  Ibs. 

2.4  Ibs. 

.9  Ibs. 

4.0  per  cent  
Fat  

2500  Ibs. 
4  per  ct. 

2125  Ibs. 
.1  per  ct. 

250  Ibs. 
.3  per  ct. 

3.0 

5.8 

94.2 

100  Ibs. 

2.1  Ibs. 

.71b. 

6.0  per  cent  
Fat—- 

1666% Ibs. 
6  per  ct. 

1417  Ibs. 
.1  per  ct. 

leribs. 

.3  per  ct. 

3.0 

4.9 

95.1 

100  Ibs. 

1.4  Ibs. 

.Sib. 

The  table  shows  that  with  2.5  per  cent.-milk,  there  is 
a  loss  of  3.4  Ibs.  of  fat  in  the  skim  milk,  a  loss  of  1.2 
Ibs.  of  fat  in  the  butter  milk,  and  of  3.0  Ibs.  in  the 
creamery  waste,  for  every  100  Ibs.  of  fat  in  the  whole 
milk,  or  a  total  loss  of  7.6  Ibs.  from  these  sources.  In 
case  of  6  per  cent,  milk  these  losses  are  1.4  Ibs.,  .5  Ib. 
and  3.0  Ibs.  for  skim  milk,  butter  milk  and  waste,  re- 
spectively; a  total  loss  of  4.9  Ibs.,  or  2.7  Ibs.  less  than 
the  losses  with  poor  milk.  This  difference  in  the  losses 


Calculation  of  Butter-  and  Cheese  Yield.        193 


shrinks  to  only  .5  pound  of  fat  in  case  of  3.5  and  4.0 
per  cent.-milk,  when  a  quantity  containing  100  Ibs.  of 
fat  is  handled  in  both  cases. 

The  overrun  from  each  of  the  four  grades  of  milk  can 
be  calculated  for  butter  containing  a  certain  per  cent, 
of  fat.  Assuming  the  fat  content  of  butter  to  be  83  per 
cent,  on  the  average  (213),  the  quantity  of  butter  ob- 
tained from  the  100  Ibs.  of  fat,  or  rather  from  the  por- 
tion thereof  which  is  available  for  butter,  in  each  case 
will  be  as  follows: 


IOC  Ibs.  of  fat  from 

Available 
fat 

Butter  cent. 
83  per  ct.  fat 

Overrun 

Lbs. 

Lbs. 

Per  cl. 

2,857  Ibs. 

93  7 

1130 

13.0 

2  500  Ibs 

94  2 

113  5 

13  5 

1.666  Ibs. 

of  6.0  per  cent  milk  

95.1 

114.6 

14.6 

The  overrun  figures  given  above  may  be  increased  by 
saving  some  of  the  three  pounds  of  butter  fat  lost  by 
waste.  If  it  were  possible  to  entirely  eliminate  this  loss 
there  would  be  three  pounds  more  available  fat  in  each 
case,  viz.,  95.4,  96.7,  97.2,  98.1  Ibs.  These  amounts  of 
fat  will  make  115,  116.5,  117.1,  and  118.2  Ibs.  butter, 
corresponding  to  an  overrun  of  15,  16.5,  17.1,  and  18.2% 
from  milk  of  the  different  fat  contents  mentioned. 

All  butter  makers  should  obtain  more  butter  from  a 
certain  quantity  of  milk  than  the  Babcock  test  shows  it 
to  contain  butter  fat,  but  it  is  impossible  to  know  ex- 
actly, except  by  chemical  analysis,  how  much  butter  fat 
is  lost  in  the  skim  milk  and  the  butter  milk,  and  how 
much  water,  salt  nnd  ourd  tlio  butter  \\ill  nontnin.  A 

13 


194 


Testing  Milk  and  its  Products. 


butter  maker's  skill  is  shown  by  his  ability  to  reduce  the. 
losses  by  waste  in  handling  the  milk,  cream  and  butter, 
as  well  as  the  losses  of  butter  fat  in  skim  milk  and  butter 
milk,  and  his  carefulness  in  weighing,  sampling  and 
testing  the  milk,  cream  and  butter  made. 

217.  Overrun  from  cream.  The  overrun  from  cream 
is,  as  already  stated,  larger  than  from  milk  because 
there  is  no  loss  of  fat  in  the  skim  milk  to  be  consid- 
ered. Rich  cream  will  give  a  slightly  larger  over- 
run than  thin  cream,  for  the  same  reasons  as  have  been 
shown  in  the  calculations  of  overrun  from  milk  of  dif- 
ferent fat  contents.  If  similar  calculations  are  made 
for  cream  of  different  richness  as  those  given  above  for 
milk,  the  fat  available  for  butter-making  and  the  yield 
of  butter  per  100  pounds  of  fat  in  the  cream  will  be 
as  shown  below.  A  mechanical  loss  in  the  process 
of  butter-making  amounting  to  1  per  cent,  has  been 
assumed  in  these  calculations: 


100  Ibs.  fat  in 
cream 

Av?ilable  fat 

Butter  of  83 
per  ct.  fat 

Overrun 

Per  cent 
20 
30 
40 

Lbs. 
96.8 
97.3 
97.6 

Lbs. 
116.6 
117.2 
117.6 

Per  cent 
16.6 
17.2 
17.6 

We  note  that  the  overrun  for  cream  of  different  qual- 
ity under  the  conditions  given  ranges  from  16.6  for  20- 
per  cent,  cream  to  17.6  for  40-per  cent,  cream.  A  some- 
what larger  overrun  would  be  obtained  when  the  butter 
made  contains  less  fat  and  more  water  than  assumed. 

If  no  losses  from  waste  are  considered  in  the  account, 
the  figures  for  fnt  available  for  butter  will  be  98.8.  00  3. 


Calculation  of  Butter-  and  Cheese  Yield.        195 

and  99.6  Ibs.,  and  the  overruns  when  the  butter  contains 
83%  fat  will  be  19,  19.3,  and  20  per  cent.  These  over- 
runs are  higher  than  will  be  obtained  under  ordinary 
creamery  conditions  with  butter  containing  83.0%  fat, 
because  it  is  impossible  to  reduce  the  manufacturing 
losses  in  handling  the  cream  and  butter  appreciably 
below  2  per  cent. 

2173.  Maximum  overrun  for  butter  of  a  legal 
water  content.  If  we  assume  that  the  butter  contains 
the  maximum  amount  of  water  allowed  by  law,  vi/.,  16 
.per  cent,  (and  therefore  about  80  per  cent,  fat),  the 
overrun  for  both  milk  and  cream  would  be  somewhat 
larger  than  already  given,  as  shown  by  the  following 
figures : 


Maximum 

overrun  from  milk 

Maximum  overrun  from  cream. 

25% 

15.5 

20%                                             "1.0 

3.5%  

17.1 

4.0% 

17  8 

60% 

18  9 

40%                                         __22.0 

This  table  shows  the  highest  overruns  that  are  likely 
to  be  obtained  when  the  butter  is  to  contain  no  more 
than  the  maximum  amount  of  water  allowed  by  law. 
Larger  overruns  can  only  be  'obtained  by  reducing  the 
losses  of  manufacture  (which  will  give  but  slightly 
higher  figures)  or,  fraudulently,  by  inaccurate  weigh- 
ing or  testing  of  the  milk,  cream  or  butter. 

218.  Calculation  of  overrun.  The  overrun  is  calcu 
lated  by  subtracting  the  amount  of  butter  fat  contained 
in  a  certain  quantity  of  milk  or  cream,  from  the  amounl 


196  Testing  Milk  and  Its  Products. 

of  butter  made  from  it,  and  linding  what  per  cent,  this 
difference  is  of  the  amount  of  butter  fat  in  the  milk. 

Example  1:  8000  Ibs.  of  milk  is  received  at  the  creamery  on 
a  certain  day;  the  average  test  of  the  milk  is  3.8  per  cent.  By 
a  simple  multiplication  we  find  that  the  milk  contained  8000  X 
.038=304  Ibs.  of  butter  fat.  350  Ibs.  of  butter  was  made  from 
this  milk,  as  shown  by  the  weights  of  the  packed  tubs.  The  dif- 
ference between  the  weight  of  butter  and  butter  fat  is,  therefore, 
46  Ibs.;  46  is  4C^°°  =15.1  per  cent,  of  the  quantity  of  the  butter 
fat  in  the  milk;  that  is,  the  overrun  for  the  day  considered  was 
15.1  per  cent. 

The  formula  for  the  overrun  is  as  follows: 
x=  (b-f)lOO 

b  and  /  designating  the  quantities  of  butter  and  butter 
fat,  respectively,  made  from  or  contained  in  a  certain 
quantity  of  milk.  In  the  preceding  example,  the  calcu- 
lation would  be  as  follows:  (iso-awxioo  =15.1  percent. 

304 

Example  2:  1000  Ibs.  of  cream  testing  25  per  cent,  fat  con- 
tains 1000 X. 25=250  Ibs.  butter  fat.  If  304  Ibs.  of  butter  is 
made,  the  overrun  may  be  calculated  by  subtracting  the  butter 
fat  from  the  butter,  304 — 250=54  Ibs.,  then  divide  this  by  the 
fat  in  the  cream  and  multiply  by  100;  or  54^100  =21.8  per  cent.. 
which  is  the  cream  overrun. 

219.  Conversion  factor  for  butter  fat.  In  the  ninety- 
day  dairy  test  at  the  World's  Columbian  Exposition. 
96.67  per  cent,  of  the  fat  in  the  whole  milk  was  recovered 
in  the  butter.  This  butter,  on  the  average,  contained 
82.37  per  cent,  butter  fat;  in  other  words,  117.3  pounds 
of  butter  were  made  from  each  100  pounds  of  butter 
fat  in  the  whole  milk.1  The  exact  conversion  factor 

'When  82.37  Ibs.  of  butter  fat  will  make  100  Ibs.  of  butter,  how 
much  butter  will  06.67  Ibs.  of  butter  fat  make?  82.37:  96.67  :  : 
100:  x,  x  =  117.3. 


Calculation  of  Butter-  and  Cheese  Yield        197 

would  be  1.173.  As  this  is  an  awkward  number  to  use, 
and  as  1%  is  so  nearly  the  same,  it  was  recommended 
at  the  time  that  the  approximate  equivalent  of  butter  be 
computed  by  multiplying  the  amount  of  butter  fat 
by  1%,  and  this  figure  has  been  generally  accepted  for 
computing  the  yield  of  butter  from  a  certain  amount  of 
butter  fat  in  milk. 

The  figures  given  are  the  result  of  more  than  ordinary 
care  in  skimming,  churning  and  testing,  and  probably 
represent  the  minimum  losses  of  fat  in  the  manufactur- 
ing processes.  The  increase  of  churn  over  test  repre- 
sented by  one-sixth,  or  16  per  cent.,  may  therefore  be 
taken  as  a  maximum  "overrun"  for  milk  under  ordi- 
nary factory  conditions. 

220.  Butter  yield  from  milk  of  different  richness. 
a.  Use  of  butter  chart.  The  approximate  yield  of  but- 
ter from  milk  of  different  richness  is  shown  in  Table  XI 
in  the  Appendix.  This  table  is  founded  on  ordinary 
creamery  experience  and  will  be  found  to  come  near  to 
actual  every-day  conditions  in  creameries  where  modern 
methods  are  followed  in  the  handling  of  the  milk  and 
its  products.  The  table  has  been  prepared  in  the  fol- 
lowing manner: 

It  is  assumed  that  the  average  loss  of  fat  in  the  skim  milk  is 
.20  per  cent.,  and  that  85  Ibs.  of  skim  milk  is  obtained  from  each 
100  Ibs.  of  whole  milk;  to  this  loss  of  fat  is  added  that  from 
the  butter  milk ;  about  10  Ibs.  of  butter  milk  is  obtained  per  100 
Ibs.  of  whole  milk,  testing  on  the  average  .30  per  cent. 

If  f  designate  the  fat  in  100  Ibs.  of  milk,  then  the  fat  recov- 
ered in  the  butter  from  100  Ibs.  of  milk  will  be 


198  Testing  Milk  and  Its  Products. 

There  is,  on  the  other  hand,  aa  increase  in  weight  in  the  but- 
ter made,  owing  to  the  admixture  of  non-fatty  components 
therein,  principally  water  and  salt.  Butter  packed  and  ready 
fer  the  market  will  contain  in  the  neighborhood  of  84  per  cent, 
of  fat  (214),  so  that  the  fat  recovered  in  the  butter  must  be  in 
creased  by  if?  =1.19.  If  B  therefore  designate  the  yield  of  but- 
ter from  100  Ibs.  of  milk,  the  following  formula  will  express  the 
relation  between  yield  and  fat  content,  provided  there  are  no 
other  factors  entering  into  the  problem,  viz.: 

B=(f— .20)  1.19 

Prom  this  value  for  B,  should  be  deducted  the  loss  due  to 
wastes  in  the  manufacturing  processes,  amounting  to  3  per  cent, 
of  the  total  fat  in  the  milk  handled,  and  we  therefore  have: 

B=(f— .20)    1.16 

Since  this  table  is  based  on  a  fat  content  of  .2  per 
cent,  in  the  skim  milk,  the  figures  for  the  overrun  are 
slightly  lower  than  may  be  obtained  in  creameries  pro- 
vided with  up-to-date  cream  separators. 

221.  Table  XI  in  the  Appendix,  founded  on  this 
formula,  may  be  used  to  determine  the  number  of 
pounds  of  butter  which  milk  containing  3  to  5.3  per 
cent,  fat  will  be  likely  to  make.  It  presupposes  good 
and  careful  work  in  separating  and  churning  and  under 
such  conditions  will  generally  show  yields  of  butter 
varying  but  little  from  those  actually  obtained.  It  may 
be  conveniently  used  by  the  butter  maker  or  the  manager 
to  check  up  the  work  in  the  creamery;  the  average  test 
of  the  milk  received  during  a  certain  period  is  found 
by  dividing  the  total  butter  fat  received,  by  the  total 
milk,  and  multiplying  the  quotient  by  100;  the  amount 
of  butter  which  the  total  milk  of  this  average  fait  con- 
tent will  make,  according  to  the  table,  is  then  compared 
with  the  actual  churn  yield. 


Calculation  of  Butter-  and  Cheese  Yield.        199 

Example:  A  creamery  receives  200,000  Ibs.  of  milk  during 
a  month;  the  milk  of  each  patron  is  tested  and  the  fat  contained 
therein  calculated.  The  sum  of  these  amounts  of  fat  may  be 
7583  Ibs;  the  average  test  of  the  milk  is  then  3.79  per  cent.  Ac- 
cording to  Table  XI,  10,000  Ibs.  of  milk,  testing  3.8,  will  make 
418  Ibs.  of  butter,  and  200,000  Ibs.,  therefore,  8360  Ibs.  of  but- 
ter. The  total  quantity  of  butter  made  during  the  month  will 
net  vary  appreciably  from  this  figure  if  the  work  in  the  cream- 
ery has  been  properly  done. 

222.  b.  Use  of  overrun  table.    The  table  referred  to 
above  gives  a  definite  calculated  butter  yield  for  each 
grade  of  milk,  according  to  average  creamery  condi- 
tions.   As  it  may  be  found  that  this  table  will  give  uni- 
formly either  too  low  or  too  high  results,  Table  XII  in 
the  Appendix  is  included,  by  means  of  which  the  butter 
yield  corresponding  to  overruns  from  10  to  20  per  cent. 
may  be  ascertained  in  a  similar  way  as  above  described. 

The  total  yield  of  butter  is  divided  by  the  total  num- 
ber of  pounds  of  fat  delivered;  the  quotient  will  give 
the  amount  of  butter  made  from  one  pound  of  fat,  and 
this  figure  multiplied  by  the  fat  delivered  by  each  pat- 
ron shows  the  pounds  of  butter  to  be  credited  to  each 
patron.  To  use  the  table,  find  in  the  upper  horizontal 
line  the  number  corresponding  nearest  to  the  number  of 
pounds  of  butter  from  one  pound  of  fat.  The  vertical 
column  in  which  this  falls  gives  the  pounds  of  butter 
from  100  Ibs.  of  milk  containing  the  per  cents,  of  fat 
given  in  the  outside  columns  (Babcock). 

B.— CALCULATION  OP  YIELD  OP  CHEESE. 

223.  a.  From  fat.    The  approximate  yield  of  green 
Cheddar  cheese  from  100  Ibs.  of  milk  may  be  found  by 
multiplying  the  per  cent,  of  fat  in  the  milk  by  2.7 ;  if  / 


200  Testing  Milk  and  Its  Products. 

designate  the  per  cent,  of  fat  in  the  milk,  the  formula 
will,  therefore,  be: 

Yield  of  cheese=2.7  f (I) 

The  factor  2.7  will  only  hold  good  as  the  average  of  a 
large  number  of  cases.  In  extensive  investigations  dur- 
ing three  consecutive  years,  Van  Slykex  found  that  the 
number  of  pounds  of  green  cheese  obtained  for  each 
pound  of  fat  in  the  milk  varied  from  2.51  to  3.06,  the 
average  figures  for  the  three  years  1892- '94,  inclusive, 
being  2.73,  2.71,  and  2.72  Ibs.,  respectively.  The  richer 
kinds  of  milk  will  produce  cheese  richer  in  fat,  and 
will  yield  a  relatively  larger  quantity  of  cheese,  pound 
for  pound,  than  poor  milk,  for  the  reason  that  an  in- 
crease in  the  fat  content  of  milk  is  accompanied  by  an 
increase  in  the  other  cheese-producing  solids  of  the 
milk.2  The  preceding  formula  would  not,  therefore,  be 
correct  for  small  lots  of  either  rich  or  poor  milk,  but 
only  for  milk  of  average  composition,  and  for  large 
quantities  of  normal  factory  milk.  For  cured  cheese 
the  factor  will  be  somewhat  lower,  viz.,  about  2.6,  on 
the  average, 

224.  b.  From  solids  not  fat  and  fat.  If  the  percent- 
ages of  solids  not  fat  and  of  fat  in  the  milk  are  known, 
the  following  formula  by  Babcock  will  give  close  results : 

Yield  of  green  cheese=l. 58  f  A_ +.91  f)     .        _     (II) 

1 N.   Y.   experiment  station    (Geneva),   bulletins   65   and    82. 

2  Investigations  as  to  the  relation  between  the  quality  of  tho  milK 
and  the  yield  of  cheese  have  been  conducted  by  a  number  of  experi- 
ment stations :  the  following  references  give  the  main  contributions 
published  on  this  point;  N.  Y.  (Geneva)  exp.  sta..  reports  10-13.  incl.: 
Wis.  exp.  sta.,  reports  11,  12,  bull.  197,  276;  Ont.  ~Agr.  College, 
reports  1894-'96,  incl.;  Minn.  exp.  sta.,  b.  19,  reports  1892-'94, 
incl.;  Iowa  exp.  sta.,  bull.  21;  Hoard's  Dairyman,  1892,  p.  2400. 


Calculation  of  Butter-  and  Cheese  Yield.        201 

s  being  the  per  cent,  of  solids  not  fat  in  the  milk,  and  / 
the'  per  cent,  of  fat.1 

The  solids  not  fat  can  be  readily  ascertained  from  the 
lactometer  reading  and  the  per  cent,  of  fat  as  shown  in 
par.  120,  by  means  of  Table  VI  in  the  Appendix. 

Table  XIII  in  the  Appendix  gives  the  yield  of  cheese 
from  100  Ibs.  of  milk  containing  from  2.5  to  6.0  per 
cent,  fat,  the  lactometer  readings  of  which  range  be- 
tween 26  and  36.  By  means  of  this  table  cheese  makers 
can  calculate  very  closely  the  yields  of  cheese  which 
certain  quantities  of  milk  will  make;  as  it  takes  into 
consideration  the  non-fatty  solids  as  well  as  the  fat  of 
the  milk,  the  results  obtained  by  the  use  of  this  formula 
will  be  more  correct  than  those  found  by  means  of 
formula  (I).  The  uncertain  element  in  the  formula  lies 
in  the  factor  1.58,  which  is  based  on  an  average  water 
content  of  37  per  cent,  in  the  green  cheese.  This  may, 
however,  be  changed  to  suit  any  particular  case,  e.  g., 
35  per  cent.  (-1^=1.54),  40  per  cent.  M=1.67,  etc. 

bo  60 

The  average  percentages  of  water  in  green  cheese  found 
by  Van  Slyke  in  his  investigations  referred  to  above, 
were  for  the  years  1892- '94,  respectively,  36.41,  37.05 
and  36.70  per  cent. 

225.  c.  From  casein  and  fat.  If  the  percentages  of 
casein  and  fat  in  the  milk  are  known,  the  yield  of  cheese 
may  be  calculated  by  the  following  formula,  also  pre- 
pared by  Dr.  Babcock: 

Yield  of  cheese=l.l  f-j-2.5  casein    ....    (III). 

This  formula  will  give  fairly  correct  results,  but  no 
more  so  than  formula  (II)  ;  it  is  wholly  empirical. 

1  For  derivation  of  this  formula,  see  Wisconsin  experiment  station, 
twelfth  report,  p.  105. 


202  Testing  Milk  and  Its  Products. 


Questions. 

1.  What    is   the    average    composition    of    American    creamery 
butter,  and  between  what  extremes  does  the  composition  of  butter 
varyT 

2.  What  is  the  difference  between  the  churn  yield  and  the  re 
suits  obtained  by  the  Babcock  testt 

3.  What  does  the  overrun  represent! 

4.  Mention  several  factors  that  cause  a  large  overrun. 

5.  Give  an  illustration   of  how  the   per  cent,  of  increase  of 
churn  over  test  is  found,  and  how  the  overrun  is  calculated. 

6.  Show  by  an  example  that  butter  containing  80%   fat  can- 
not give  an  overrun  of  more  than  25%. 

7.  How  many  pounds  of  butter  containing  80%  fat  can  be 
made   from   100   Ibs.    fail 

8.  Why  is  the  overrun  from  cream  greater  than  from  milkT 

9.  What  is  the   overrun   when   70.5   Ibs.   of  butter   are  made 
from  140  Ibs.  of  milk,  testing  3.15  per  cent? 

10.  What  is  the  overrun  in  each  of  the  following   cases  i 
•220  Ibs.  butter  from  8000  Ibs.  milk,  testing  2.3%  fat. 

250  Ibs.  butter  from  4000  Ibs.  milk,  testing  5.8%  fat. 
600  Ibs.  butter  from  2000  Ibs.  cream,  testing  25.0%  fat. 
480  Ibs.  butter  from  1000  Ibs.  cream,  testing  40.0%  fat. 

11.  How  much  butter  containing  (a)  80%  fat,  and  (b)  82.5% 
fat  can  be  made  from  3250  Ibs.  milk,  testing  4.3%  fat,  assum- 
ing that  the  skim  milk  is  80%  of  the  whole  milk  and  contains 
0.1%  fat,  and  the  butter  milk,  which  is  the  cream  minus  the  fat, 
contains  0.25%  fatf     What  is  the  overrun  in  each  case? 

12.  How  much  butter  is  obtained  from  5800  Ibs.  milk,  testing 
3.7%  fat,  when  the  overrun  is  (a)  12.5%  and  (b)   16%  f 

13.  Two  cows  in  full  milk  produce,  one  17.5  Ibs.  of  milk  a  day, 
containing  4.35%  fat;  the  other,  27.3  Ibs.  of  milk,  testing  3.4%. 
Ff   the  milk  of  both   is  made  into  butter  or   cheese,   how   much 
butter  or  cheese  may  be  expected  from  each  one  in  a  week! 

14.  What  is  a  fair  percentage  of  loss  of  fat  by  waste  other 
than  in  skim  milk  and  butter  milk  under  average  creamery  con- 
ditions in  case  of  milk  and  cream? 

15.  How  much  butter  may  be  made  from  (a)  15,640  Ibs.  milk, 
testing  3.8%   fat,  and    (b)    35,842  Ibs.  milk,  testing  4.1%   fat! 
(Use  Table  XI,  Appendix.) 


CHAPTER  XIII. 
CALCULATING  DIVIDENDS. 

A. — CALCULATING  DIVIDENDS  AT  CREAMERIES. 

226.  The  simplest  method  of  calculating  dividends  at 
creameries  is  to  base  the  calculations  on  the  amount  of 
butter  fat  delivered  by  the  various  patrons.    Each  lot 
of  milk  is  weighed  when  delivered  at  the  creamery,  and 
a  small  quantity  thereof  is  saved  for  the  composite  sam- 
ple,   as   previously    explained    under    Composite  Tests 
(180).     Some  creameries  test  these  samples  at  the  end 
of  each  week,  and  others  after  collecting  them  for  ten 
days  or  two  weeks.    If  the  four  weekly  composite  sam- 
ples of  a  patron's  milk  tested  3.8,  4.0,  3.9,  4.1  per  cent., 
these  four  tests  are  added  together,  and  the  sum  divided 
by  4;  the  result,  3.95  per  cent.,  is  used  as  the  average 
test  of  this  milk.    By  multiplying  the  total  number  of 
pounds  of  milk  delivered  by  this  patron,  by  his  average 
test,  the  total  weight  of  butter  fat  in  pounds  delivered 
to  the   factory   during  the  month   is  obtained.    This 
weight  of  fat  is  then  multiplied  by  the  price  to  be  paid 
by  the  creamery  per  pound  of  butter  fat;  the  product 
shows  the  amount  of  money  due  this  patron  for  the  milk 
delivered  during  the  time  samples  were  taken. 

227.  Price  per  pound  of  butter  fat.    The  method  of 
obtaining  the  price  to  be  paid  for  one  pound  of  butter 
fat  varies  somewhat  in  different  creameries,  on  account 
of  the  different  ways  of  paying  for  the  cost  of  manu- 


204  Testing  MUk  and  Its  Products. 

facturing  the  butter.  The  method  to  be  followed  is 
generally  determined  by  agreement  between  the  manu- 
facturer and  the  milk  producers,  in  case  of  proprietary 
creameries,  or  among  the  shareholders,  in  co-operative 
creameries.  The  following  methods  of  paying  for  the 
cost  of  manufacture  are  at  the  present  time  in  use  in 
American  creameries. 

228.  I.  Proprietary  creameries.  First. — When  the 
creamery  is  owned  by  some  one  person  or  company,  the 
owner  or  owners  agree  to  make  the  butter  for  about  3 
cents  a  pound ;  the  difference  between  the  total  receipts 
of  the  factory  and  the  amount  due  the  owner  is  then 
divided  between  the  different  patrons,  according  to  the 
amount  of  butter  fat  contained  in  the  milk  which  they 
delivered. 

The  price  charged  for  making  butter  varies  from  2'{. 
to  4  cents  per  pound;  the  larger  the  amount  of  milk 
received  at  a  factory,  the  lower  will  naturally  be  the  cost 
of  manufacturing  the  butter.1 

Second.— The  proprietor  of  the  creamery  sometimes 
agrees  to  pay  a  certain  price  for  100  Ibs.  of  milk  deliv- 
ered, according  to  its  fat  content,  the  price  of  milk  con- 
taining 4  per  cent,  of  butter  fat  being  the  standard. 
This  price  may  be  changed  during  the  different  seasons 
of  the  year  by  mutual  agreement. 

Third.— A  creamery  owner  may  offer  to  pay  1  to  2 
cents,  usually  iy2  cents,  below  the  average  market  price 
of  butter,  for  each  pound  of  butter  fat  received  in  the 
milk. 

1  Bull.  56,  p.  26,  Wisconsin  exp.  station  ;  see  Report  18,  Iowa  State 
Dairy  Commissioner,  p.  33. 


Calculating  Dividends.  205 

229.  II.       Co-operative      creameries.       Where     the 
cieamery  is  owned  by  the  patrons,  one  of  the  stock- 
holders who  is  elected  secretary  attends  to  the  details  of 
running  the  factory  and  selling  the  product.     His  ac- 
counts show  the  amount  of  money  received  each  month 
for  the  butter  and  other  products  sold,  and  the  expenses 
of  running  the  factory  during  this  time.     The  expenses 
are  subtracted  from  the  receipts,   and  the  balance  is 
divided  among  the  patrons,  each  one  receiving  his  pro- 
portionate share  according  to  the  amounts  of  butter  fat 
delivered  in  each  case,  as  shown  by  the  total  weight  and 
the  average  test  of  milk  delivered  during  this  time. 

In  nearly  all  cases,  the  farmers  receive  about  eighty 
pounds  of  skim  milk  for  each  one  hundred  pounds  of 
whole  milk  they  deliver  to  the  factory,  in  addition  to 
the  amount  received  for  the  milk,  calculated  according 
to  one  or  the  other  of  the  preceding  methods. 

230.  Illustration    of   calculation    of   dividends.     In    order 
to  illustrate  the  details  of  calculating  dividends,  or  the  amount 
to     be     paid     each     patron     for     the     milk     delivered,     when 
payments  are  made  by  each  of  the  four  systems  given,  it  will  be 
assumed  that  a  creamery  receives  5000  pounds  of  milk  daily  during 
a  month,  and   makes  6650  Ibs.  of  butter  from  the   150,000  Ibs. 
of  milk  received  during  this  time.     The  average  test  of  this  milk 
may  be  found  by  multiplying  the  total  weight  of  milk  delivered 
by   each  patron  by  bis  average  test,  and  dividing  the  sum   of 
these  products  by  the  total  weight  of  milk  received  at  the  cream- 
ery (in  the  example  given,  by  150,000),  the  quotient  being  mul- 
tiplied by  100.     Such  calculations  may  show  that,  e.  g.,  5700  Ibs. 
of  butter  fat  have  been  received  in  all  the  milk  delivered  by  the 
different  patrons;  this  multiplied  by  100  and  divided  by  150,000 
gives  3.8  aa  the  average  test,  or   the  average  amount  of  butter 
fat  in  each  100  Ibs.  of  milk  received  during  the  month. 

So  far  the  method  of  calculation  is  common  for  the  different 
systems  of  payment  given  above;  the  manner  of  procedure  now 


206 


Testing  Milk  and  Its  Products. 


differs  according  to  the  agreement  made  between  owner  and 
patrons,  or  among  the  shareholders,  in  case  of  co-operative 
creameries. 

231.  I.  First.— It  the  net  returns  for  the  6650  Ibs.  of  butter 
sold  during  the  month  were  $2394,  and  the  creamery  is  to  re- 
ceive 4  cents  per  pound  of  butter  as  the  cost  of  manufacture, 
etc.,  the  amount  due  the  creamery  is  6650X.04=$266,  and  the 
patrons  would  receive  $2394 — $266 =$2128.  This  sum,  $2128, 
is  to  be  paid  to  the  patrons  for  the  5700  Ibs.  of  butter  fat, 
which,  as  shown  above,  was  the  weight  of  fat  contained  in 
the  150,000  Ibs.  of  milk  delivered  during  the  month.  The 
price  of  one  pound  of  butter  fat  is  then  easily  found:  $2128-=- 
5700  =  37%  cents.  This  price  is  paid  to  all  patrons  for  each 
pound  of  butter  fat  delivered  in  their  milk  during  the  month. 
The  monthly  milk  record  of  three  patrons  may,  e.  g.,  be  as 
given  in  the  following  table: 


Pat  on 

First 
week 

Second 
week 

Third 
week 

Fourto 
week 

Total 
Milk 

Average 
test 

Milk 

Test 

Milk 

Test 

Milk 

~Lbs7 
3600 
720 
1850 

Test 

Milk 

Test 

No.  !___. 
No.  2  

No.  3  

Lbs. 
3500 
700 
2480 

ti 

3.8 
4.2 

Lbs. 
3000 

2000 

3?5 
3.8 
3.8 

3i6 
4.0 

Lbs. 
3450 
750 
1500 

3.45 
3.7 
3.6 

Lbs. 
13,550 
2.825 
7,830 

3.73 

3.90 

Multiplying  each  patron's  total  milk  by  his  average  test  gives 
the  number  of  pounds  of  butter  fat  in  his  milk,  and  this  figure 
multiplied  by  .37%  shows  the  money  due  for  his  milk,  as 
given  below: 


Patron 

Total 
milk 

Average 
test 

Butter 
fat 

Price  of  fat 
per  Ib. 

Amount 
due 

No.  1 

Lbs. 
13,550 

Per  cent 
3.55 

Lbs. 
^81   0 

Cents 
37  H 

$179  41 

No   2 

2  8b5 

3  7 

104  5 

37  j£ 

38  98 

No.  3  

7,830 

3.9 

305!  4 

37  H 

113.91 

232.  Second. — When  the  proprietor  of  a  creamery  agrees  to 
pay  a  certain  price  for  100  Ibs.  of  4  per  cent,  milk,  the  receipts 
for  butter  sold  and  the  price  per  pound  of  butter  do  not  enter 
into  the  calculation  of  the  amount  due  each  patron  for  his  milk; 


Calculating  Dividends. 


207 


but  the  weight  and  the  test  of  each  patron's  milk  are  as  im- 
portant as  before.  If  it  is  agreed  to  pay  $2.50  per  100  Ibs. 
of  4  per  cent,  milk  (i.  e.,  milk  containing  4  per  cent,  of  butter 
fat),  the  price  of  one  pound  of  butter  fat  will  be  $2.50-f-4  = 
62.5  cents,  and  the  amount  due  each  patron  is  found  by  multi^ 
plying  the  total  weight  of  butter  fat  in  his  milk  by  this  price. 
To  facilitate  this  calculation,  so-called  Relative-Value  Tables 
have  been  constructed,  the  use  of  which  is  explained  below 
(238). 

233.  Third. — If  a  creamery  agrees  to  pay  for  butter  fat,  saj 
1  cent  per  pound  below  the  average  market  price  of  butter 
each  month,  the  price  of  one  pound  of  butter  fat  is  found  by 
averaging  the  market  quotations  and  subtracting  1  cent  there- 
from. If  the  four  weekly  market  prices  were  37,  38,  37  and 
40  cents,  the  average  of  these  would  be  38  cents,  and  this  less 
1  cent  gives  37  cents  as  the  price  per  pound  of  fat  to  be  paid 
to  the  patrons;  this  price  is  then  used  in  calculating  the  di- 
vidend as  in  case  of  first  method. 


Patron 

Total 
milk 

Average 
test 

Butter 
fat 

Price  of  fat 
per  Ib. 

Amount 
due 

Xo.  1   „ 

Lbs. 
13,550 

Per  cent 
3.55 

Lbs. 
481.0 

Cents 
37 

$177.97 

No.  2         

2,825 

3.7 

104.5 

37 

38.67 

No   3 

7,830 

3.9 

305.4 

37 

113.00 

234.  II.  If  the  creamery  is  owned  by  the  farmers,  the  run- 
ning expenses  for  a  month  are  subtracted  from  the  gross  returns 
received  for  the  butter,  and  the  price  to  be  paid  per  pound  of 
butter  fat  is  found  by  dividing  the  amount  left  by  the  total 
number  of  pounds  of  butter  fat  delivered  during  the  month. 
This  price  is  used  for  paying  each  patron  for  his  milk  according 
to  the  amount  of  fat  contained  therein,  as  already  explained  un- 
der Proprietary  Creameries  (231). 

The  monthly  running  expenses  of  a  co-operative  creamery  gen- 
erally include  such  items  as  the  wages  of  the  butter  maker  (and 
manager  or  secretary,  if  these  officers  are  salaried),  labor  (haul- 
ing, helper,  etc.),  cost  of  butter  packages,  coal  or  wood,  salt 
and  other  supplies,  freight  and  commission  on  the  butter  sold, 
repairs  and  insurance  on  buildings,  etc.  A  certain  amount  is 
also  paid  into  a  linking  fund  (say,  5  cents  per  100  Ibs.  of  milk), 


208  Testing  Milk  and  Its  Products. 

which  represents  the  depreciation  of  the  property,  wear  and  tear 
of  building  and  machinery,  bad  debts,  etc.  These  items  are 
added  together,  and  their  sum  subtracted  from  the  gross  receipts 
for  the  butter  sold  during  the  month. 

235.  Assuming  the  receipts  for  the  butter  during  the  month 
to  be  $2394,  and  the  running  expenses  of  the  factory  $285,  the 
amount  to  be  divided  among  the  patrons  is  $2109;  the  quan- 
tity of  butter  fat  received  was  5700  Ibs.,  and  the  price  per 
pound  of  butter  fat  will  therefore  be  37  cents.     The  account 
will  then  stand  as  given  in  (233). 

236.  Other  systems  of  payment.    Besides  these  four 
systems  of  payment,  there  are  various  other  agreements 
made   between  manufacturer   and   producer,   but  with 
them  all  the  one  important  computation  is  the  price  to 
be  paid  per  pound  of  butter  fat ;  this  forms  the  basis  of 
calculating  the  factory  dividends,  when  milk  is  paid  for 
by  the  Babcock  test. 

237.  Paying  for  butter  delivered.   In  some  instances 
patrons  desire  to  receive  pay  for  the  quantity  of  butter 
which  the  milk  or  cream  delivered  by  them  would  make 
This  can  be  ascertained  quite  satisfactorily  from  the  total 
receipts  and  the  total  weights  of  both  butter  fat  and  but- 
ter.   The  total  money  to  be  paid  for  butter  (the  net  re- 
ceipts) are  divided  by  the  number  of  pounds  of  butter 
sold,  to  get  the  price  to  be  paid  per  pound  of  butter;  the 
total  yield  of  butter  divided  by  the  total  amount  of 
butter  fat  delivered  in  the  milk,  gives  the  amount  of 
butter  corresponding  to  one  pound  of  butter  fat,  and 
the  number  of  pounds  of  fat  delivered  by  each  patron 
is  then  multiplied  by  this  figure.     This  method  requires 
more  figuring  than  those  given  in  the  preceding,  and  the 
dividends  are  no  more  accurate,  in  fact  less  so,  than 
when  calculations  are  based  on  tlie  price  per  pound  of 
fat. 


Calculating  Dividends.  209 

2373.  Making  butter  "for  the  overrun."  When 
cream  is  bought  on  the  basis  of  paying  the  market  price 
of  butter  for  each  pound  of  butter  fat  in  the  cream,  the 
margin  received  by  the  cream  buyer,  if  he  makes  this 
cream  into  butter,  is  influenced  both  by  the  price  of 
butter  and  the  per  cent,  of  overrun  he  obtains.  If  the 
price  of  butter  is  20c.  and  the  overrun  is  20%,  each 
pound  of  butter  fat  makes  1.2  Ibs.  of  butter,  and  the 
buyer  receives  24  cents  for  the  butter,  or  4  cents  margin 
on  the  1.2  Ibs.  of  butter  made,  which  is  equal  to  3V-} 
cents  per  pound  of  butter.  If  the  price  of  butter  is 
36  cents,  and  the  overrun  20%,  the  cream  buyer  receives 
1.2X36=43  cents  for  the  butter,  or  7  cents  for  1.2  Ibs. 
of  butter,  equivalent  to  5.8  c.  per  pound  of  butter. 

238.  Relative-value  tables.  These  tables  give  many 
of  the  multiplications  used  in  computing  the  amount 
due  for  various  weights  of  milk  of  different  fat  con- 
tents. They  can  easily  be  constructed  by  any  one 
as  soon  as  the  price  of  one  pound  of  fat  is  determined 
in  each  case.  If  the  price  to  be  paid  per  pound  of  fat 
is,  say  25  cents,  the  value  of  each  100  Ibs.  of  milk  of 
different  quality  is  found  by  multiplying  its  test  by  25. 
If  the  average  tests  of  the  different  patrons'  milk  vary 
from  3  to  5  per  cent.,  the  relative- value  table  would  be 
as  follows. 

3.6X25=90c.  per  100  Ibs. 

3.7 X 25=92  5c. 

3.8X25=95.0c.         " 

3.9X25=97.5c. 

4.0X25=100c.          " 
etc. 


.TOX25:=75c.    per  100  Ibs. 

3.lX25=77.5c. 

3.2X25=80c. 

3.3X25=82.5c. 

3.4X25=85.0c. 

3.5X25=87.5c. 


By  continuing  this  multiplication,  or  adding  the  mul- 
tiplier each  time  for  each  tenth  of  a  per  cent,  up  to  5 


210 


Testing  Milk  and  Its  Products. 


per  cent,  of  fat,  a  table  is  made  that  can  be  used  for 
calculating  the  amount  due  per  100  Ibs.  of  milk  at  the 
price  per  pound  given,  and  the  weight  of  milk  delivered 
by  each  patron  is  multiplied  by  the  price  per  100  Ibs.  of 
milk  shown  in  the  table  opposite  the  figure  representing 
his  test. 

Example:  A  patron  supplies  2470  Ibs.  of  milk,  testing  3.2 
per  cent,  of  fat;  price  per  pound  of  fat,  25  cents;  he  should 
then  receive  24.70  X.80=$19.76  (see  above  table).  Another  pat 
ron  delivering  3850  Ibe.  of  milk  testing  3.8  per  cent,  will  re 
ceive,  at  the  same  price  per  pound  of  fat,  38.50 X.95=$35.57. 

The  relative-value  tables  in  the  Appendix  give  the 
price  per  100  Ibs.  of  milk  testing  between  3  and  6  per 
cent,  fat,  when  the  price  of  three  per  cent,  milk  varies 
from  30  to  90c.  per  100  Ibs.  In  using  the  tables,  first 
find  the  figure  showing  the  price  which  it  has  been  de- 
termined to  pay  for  100  Ibs.  of  milk  of  a  certain  qual- 
ity, say  3  or  4  per  cent.-milk;  the  figures  in  the  same 
vertical  column  then  give  the  price  to  be  paid  per  100 
Ibs.  of  milk  testing  between  3  and  6  per  cent. 

Example  1 :  It  has  been  decided  to  pay  90  cents  per  100  Ibs. 
of  4  per  cent.-milk.  The  figure  90  is  then  sought  in  the  table  in 
the  same  line  as  4.0  per  cent.,  and  the  vertical  column  in  which 
it  is  found  gives  the  price  per  100  Ibs.  of  3  to  6  per  cent.-milk ; 
3.8  per  cent-milk  is  thus  worth  85  cents  per  100  Ibs.  and  4.5  per 
cent.-milk,  $1.01.  under  the  conditions  given.  The  prices  of  milk 
of  other  qualities  are  found  in  the  same  way. 

Example  2:  In  the  example  referred  to  under  Illustrations  of 
calculating  creamery  dividends  (I  b,  231),  the  figures  for  the 
patrons  Nos.  1,  2  and  3,  would  be  as  follows: 


Patron 

Milk  delivered 

Average 
test 

Price  per  100 
Ibs.  of  milk 

Amount 
due 

Lbs. 

Per  cent 

Cents 

So.  1... 

13,550 

3.55 

58.5 

$79.26 

o.  2... 
No.  3.      . 

2,825 
7,830 

3.7 

3.9 

61.1 
64.0 

17.23 
50.11 

Calculating  Dividends.  211 

239.  Milk-  and  cream  dividends.   When  cream  from 
farm  hand  separators  or  other  sources  is  brought  to  a 
factory  receiving  and  skimming  whole  milk,  the  cream 
patron's  dividend  should  be  calculated  a  little  differ- 
ently than  that  of  the  milk  patron   (210). 

In  one  case  the  dividend  is  based  on  the  weight  and 
the  test  of  cream  and  in  the  other  on  the  weight  and 
the  test  of  milk;  the  difference  between  the  two  being 
represented  by  the  fat  left  in  the  factory  skim  milk. 
This  skim  milk  fat  is  included  in  the  milk  patron's 
dividend  and  consequently  ought  also  to  be  allowed  for 
in  calculating  the  amount  due  the  cream  patron.  Such 
an  allowance  can  be  fairly  made  by  multiplying  the 
cream  fat  by  1.03.  The  amounts  of  fat  thus  obtained 
represent  very  nearly  the  fat  in  the  milk  from  which 
the  cream  was  skimmed  and  assumes  that  the  fat  re 
turned  to  the  milk  patron  in  his  skim  milk  is  abou' 
three  per  cent,  of  the  total  fat  in  his  whole  milk. 

Since  both  milk  and  cream  patron  suffer  the  same 
manufacturing  losses  in  the  butter  milk,  an  equalixa- 
tion  of  the  skimming  losses  is  all  that  is  necessary  in 
order  to  put  both  on  a  uniform  basis  for  calculating 
dividends. 

240.  The   following    illustration   will  help   to    make   these   cal- 
culations   clearer.     Milk   patron   No.   1    delivers  to   the  creamery 
during  the   month   5320   Ibs.   of  milk   testing   3.8   per  cent,   fat, 
which  therefore  contain*  (  ^y^-)  =202  Ibs.  butter  fat.     If  the 
price  paid  ilie  pntrons  is  20c.,  then  202  multiplied  by  20  amounts  to 
$40.40,  the  money  due  this  patron  for  his  milk.     If  another  pat- 
ron sent  485  Ibs.  of  cream  testing  22.0  per  cent,  fat  to  the  same 
factory  during  the  month,  the  weight -of  fat  in  the  cream  is  first 
found  in  the  same  way  as  in  the  milk.     (  ^jjjp  )  =106.7  Ibs.  but 


212    .  Testing  Milk  and  Its  Products. 

ter  fat.  Now,  instead  of  multiplying  this  butter  fat  by  20c.,  as 
was  done  for  the  whole  milk  patron,  it  must  first  be  multiplied 
by  1.03.  106.7X1.03=109.9  Ibs.  butter  fat  which  is  now  multi- 
plied by  20c.  per  pound,  giving  $21.98.  This  is  the  amount  due 
the  cream  patron  when  both  milk  and  cream  are  received  at  the 
same  factory  and  the  cream  from  both  patrous  is  churned  to 
gether.1 

241.  The  amount  of  cheese  made  from  a  certain  quan- 
tity of  milk  depends,  as  before  shown,  in  a  large  meas- 
ure on  the  richness  of  the  milk  in  butter  fat  (223). 
Rich  milk  will  give  more  cheese  per  hundred  weight 
than  poor  milk,  and  within  the  ordinary  limits  of  nor- 
mal factory  milk  the  increased  yields  will  be  nearly,  but 
not  entirely,  proportional  to  the  fat  contents  of  the  dif- 
ferent kinds  of  milk.  Since  the  quality  of  the  cheese 
produced  from  rich  milk  is  better  than  that  of  cheese 
made  from  thin  milk  and  will  demand  a  higher  price, 
it  follows  that  no  injustice  is  done  by  rating  the  value 
of  milk  for  cheese  production  by  its  fat  content.  This 
subject  was  discussed  frequently  during  the  nineties  in 
experiment  station  publications  and  in  the  dairy  press 
(223).  Among  others,  Babcock  has  shown  that  the  price 
of  cheese  stands  in  a  direct  relation  to  its  fat  content.2 
Prof.  Robertson,  ex-Commissioner  of  Agriculture  of  Can- 
ada, is  authority  for  the  statement  that  the  quality  of 
the  cheese  made  from  milk  containing  3.0  to  4.0  per 
cent,  of  fat  was  increased  in  value  by  one-eighth  of  a 
cent  per  pound  for  every  two-tenths  of  a  per  cent,  of 
fat  in  the  milk,3  a  figure  which  is  fully  corroborated  by 

1  17th   report   Wis.   oxp.   station,   p.  !)0  :   COtli   report,   pp,   1,'W-lf!1. 

2  Wisconsin  exp.  station,  llth  report,  p.  134. 
"Hoard's  Dairyman.  March  29,  1895. 


Calculating  Dividends.  213 

Dr.  Babcock's  results.  The  injustice  of  the  "pooling 
system,"  by  which  all  kinds  of  milk  receive  the  same 
price,  is  evident  from  the  preceding;  if  the  milk  of  a 
certain  patron  is  richer  than  that  of  others,  it  will  make 
a  higher  grade  of  cheese,  and  more  of  it  per  hundred- 
weight; hence  a  higher  price  should  be  paid  for  it. 

Payment  on  the  basis  of  the  fat  content  of  milk  is, 
therefore,  the  most  equitable  method  of  valuing  milk 
for  cheese  making,  and  in  case  of  patrons  of  cheese  fac- 
tories as  with  creamery  patrons,  dividends  should .  be 
calculated  on  the  basis  of  the  results  obtained  by  test- 
ing the  milk  delivered.  The  testing  may  be  conven- 
iently arranged  by  the  method  of  composite  sampling, 
in  the  way  already  described  for  creameries  (180). 

242.  Cheese  factory  dividends,  (a)  Dividends 
based  on  fat  test  alone.  As  in  the  case  of  creameries, 
the  price  to  be  paid  per  pound  of  butter  fat  must  first 
be  ascertained.  The  factory  records  should  show  the 
number  of  pounds  of  cheese  made  from  the  total  milk 
delivered  to  the  factory  during  a  certain  time,  generally 
one  month,  and  the  money  received  for  this  cheese.  The 
cost  of  making  the  cheese  and  all  other  expenses  that 
should  be  paid  for  out  of  the  money  received  for  the 
cheese,  are  deducted  from  the  total  receipts,  and  the 
difference  is  divided  among  the  patrons  in  proportion 
to  the  amounts  of  butter  fat  delivered  in  the  milk. 

The  weights  of  the  milk  delivered  and  the  tests  of  the 
composite  samples  furnish  data  for  calculating  the 
quantities  of  butter  fat  to  be  credited  to  each  patron 


214  Testing  Milk  and  Its  Products. 

The  money  to  be  paid  to  the  patrons  is  then  divided  by 
the  total  weight  of  butter  fat  delivered  to  the  factory 
and  the  price  of  one  pound  of  fat  thus  obtained.  The 
money  due  each  patron  is  now  found  by  multiplying 
the  total  number  of  pounds  of  butter  fat  in  his  milk  by 
this  price  per  pound. 

(b)  Dividends  based  on  fat  and  solids-not-fat  (lacto- 
meter readings).     A  close  estimate  of  the  cheese  value 
of  each  patron's  milk  may  be  made,  as  explained  in 
par.  224,  b.,  by  the  use  of  table  XIII  in  the  Appendix. 
When  the  cheese  yield  of  each  patron's  milk  is  found  by 
this  method,  the  money  to  be  distributed  among  the 
patrons  is  divided   by   the   sum   of   the   figures   found 
by  these  two  tests,  instead  of  by  the  total  butter  fat.  The 
figure  thus  obtained  is  the  price  to  be  paid  each  patron 
per  pound  cheese  that  may  be  made  from  his  milk  as 
shown  by  both  the  fat  test  and  the  lactometer  reading. 

(c)  Dividends  based  on  "the  fat  plus  two  method." 
The  money  due  patrons  for  milk  delivered  at  cheese 
factories  may  be  calculated  by  adding  two  to  the  per 
cent,  of  fat  in  the  milk,  and  otherwise  proceeding  as 
explained  above  under  par.  242a.     This  is  the  method 
advocated  by  Prof.  H.  H.  Dean  of  Guelph  (Ont.)  Ag- 
ricultural college.1    It  has  been  adopted  at  many  Cana- 
dian cheese  factories  and  at  some  factories  in  this  coun- 
try. 

(d)  Dividends  based  on  the  fat  and  casein  tests.  The 
results  obtained  by  the  fat  test  and  the  Hart  casein 

1  Bull.  114.  Ont.  Aer    College:  we  also  Dean.  Canadian  Dairying,  o. 
146,  and  Sammis,  Wisconsin  station,  bull.   276. 


Calculating  Dividends.  215 

test  (258)  are  added  together;  the  pounds  of  milk  de 
livered  by  each  patron  are  multiplied  by  this  figure 
and  the  product  multiplied  by  the  price  to  be  paid  foi 
the  sum  of  the  fat  and  the  casein.1  This  price  per 
pound  is  obtained  in  the  same  way  as  the  price  per 
pound  of  fat.  Each  patron's  milk  is  multiplied  by  the 
sum  of  the  fat  and  the  casein  tests  and  the  money  to 
be  distributed  to  the  patrons  is  divided  by  the  sum  of 
these  figures  obtained  for  all  patrons  for  the  period 
covered. 

The  illustrations  already  given  for  calculating  patrons' 
dividends  at  creameries  according  to  the  various  meth- 
ods will  serve  equally  well  to  show  the  manner  in  which 
dividends  are  calculated  at  a  cheese  factory.  For  the 
sake  of  clearness  an  example  is  given  that  applies  di- 
rectly to  cheese  factories. 

243.  Illustration    of    calculation    dividends.      It  may  be 

assumed  that  15,000  libs,  of  green  cheese  is  made  from  150,000 
Ibs.  of  milk  delivered  to  a  factory  in  a  month.  According  to  the 
weighings  and  the  tests  made,  the  milk  contained  5,700  Ibs.  of 
butter  fat.  If  the  cheese  sold  at  an  average  price  of  20  cents 
a  pound,  the  gross  receipts  would  be  $3,000.  The  amount  to 
be  deducted  from  the  gross  receipts  will  depend  on  the  agree- 
ment made  between  the  factory  operator  and  the  patrons,  in 
case  of  proprietary  cheese  factories,  or  between  the  shareholders 
and  the  maker,  when  the  factory  is  run  on  the  co  operative  plan. 
As  before  we  shall  consider  these  systems  separately. 

244.  I.     Proprietary   cheese   factories.       The  owner  of  the 
factory  generally  agrees  to  make  the  cheese  for  a  certain  price 
per  pound  and  to  pay  the  patrons  what  is  left  after  deducting 
this  amount.     If  the  price  agreed  on  is  2  cents  per  pound  of 
green  cheese,  this  would  amount  to  $300  in  the  example  given. 
Subtracting  this  sum  from  the  gross  receipts,  $3,000,  leaves 

1  Wisconsin  oxpt.  station,  null    107 


216 


Testing  Milk  and  Its  Products 


$2,700  which  is  to  be  paid  the  patrons.  The  total  amount  of 
butter  fat  delivered  by  the  patrons  was  5,700  Ibs.,  hence  the 
price  of  one  pound  of  butter  fat  will  ba  2,700-^5,700  =  .2111, 
or  21  cents.  Taking  the  figures  for  the  three  patrons  al- 
ready mentioned  under  Creamery  Dividends,  we  then  have : 


Patron 

Total 
milk 

Average 
test 

Butter 
fat 

Price  per 
Ib.  of  fat 

Amount 
due 

No.  I... 

Lbs. 
13,350 

Per  cent 
3.55 

Lbs. 
481.0 

Cents 
21 

$101.01 

No.  2 

2*825 

3.7 

104.5 

21 

21  .94 

No    3 

7  830 

3.9 

305.4 

21 

64  .  1  3 

245.  II.  Co-operative  cheese  factories.  The  method  of  pay- 
ment at  co-operative  cheese  factories  is  nearly  the  same  as  that 
already  given,  except  that  a  certain  sum  representing  the  ex- 
penses is  subtracted  from  the  gross  receipts  for  the  cheese,  and 
the  balance  is  divided  among  the  patrons  according  to  the  amount 
of  butter  fat  furnished  by  each,  in  the  same  manner  as  in  the 
above  case,  after  the  price  of  a  pound  of  fat  has  been  obtained. 

The  price  per  100  Ibs.  of  milk  can  be  calculated  in  the  same 
way  as  at  creameries,  by  multiplying  the  test  of  each  lot  by  the 
price  per  pound  of  fat.1 


Questions. 

1.  How  much  money  is  due  each  of  three  patrons  of  a  cream- 
ery when  the  following  weights  of  milk  are  delivered  by  each: 
A —   5750   Ib.  milk,   composite  tests,  4.0 — 4.8 — 4.2  per  cent. 
B —      955  Ib.  milk,   composite  tests,   4.6 — 5.0 — 4.8  per   cent. 
C — 10,538  Ib.  milk,   composite  tests,  3.2 — 3.5 — 3.0   per   cent. 

(a)  When  700  Ibs.  of  butter  are  sold  for  $200,  and  the  cost  of 
making  is  3%c.  per  Ib; 

(b)  When  the  factory  agrees  to  pay  $1.00  per  100  Ibs.  milk, 
testing  4%  fat; 

1  Suggestions  regarding  the  organization  of  co-operative  creameries 
and  cheese  factories  will  be  found  in  the  Appendix,  following  Table 
XV.  Draft  of  constitution  and  by-laws  for  co-operative  factory  as 
sociations  are  also  given  in  the  Appendix.  It  is  hoped  that  those  will 
prove  helpful  to  farmers  who  contemplate  forming  such  associations 


CHAPTER  XIV. 

CHEMICAL  ANALYSIS  OF  MILK  AND  ITS 
PRODUCTS. 

246.  An  outline  of  the  methods  followed  in  determin- 
ing quantitatively  the  main  components  of  milk  and  its 
products  is  given  in  the  following  for  the  guidance  of 
advanced  dairy  students.     This  work  cannot  be  done 
outside  of  a  fairly  well-equipped  chemical   laboratory, 
or  by  persons  who  have  not  been  accustomed  to  handling 
delicate   chemical   apparatus   and   glassware,   analytical 
balances,   etc.,   and   who  have  not  a  knowledge  of,   at 
least,  the  elements  of  chemistry  and  chemical  reactions 

A. — MILK. 

247.  In  a  complete  milk  analysis,  the  specific  gravity 
of  the  milk  is  determined,  and  the  following  milk  com 
ponents :  water,  fat,  casein  and  albumen,  milk  sugar, 
and  ash.     The  methods  of  analysis  described  in  the  fol 
lowing  are  those  adopted  by  the  Association  of  Official 
Agricultural   Chemists  of  North  America,   which,   with 
hut  slight  modifications,  are  in  general  use  in  the  chemi- 
cal laboratories  of  all  American  experiment  stations  and 
agricultural  colleges.1 

248.  a.  Specific  gravity  is  determined  by  means  of 
a  picnometer  or  specific-gravity  bottle,  since  more  ac- 

1  The  complete  methods  of  analysis  adopted  l>y  tho  Association  of 
Official  Agricultural  Chemists  are  published  l>y  tho  r?ur.  of  Chemistry 
of  the  U.  S.  Department  of  Agriculture;  see  Hull.  No.  107.  pp.  I17-12S. 


218  Testing  Milk  and  Its  Products. 

curate  results  will  thus  be  reached  than  by  using  an  or- 
dinary Quevenne  lactometer.  A  thermometer  is  ground 
into  the  neck  of  the  specific-gravity  bottle  so  as  to  form 
a  stopper,  and  the  bottle  is  provided  with  a  glass-stop- 
pered side-tube,  to  furnish  an  exit  for  the  liquid  on  ex- 
panding. A  specific-gravity  bottle  holding  100  grams 
of  water  is  preferably  used.  The  empty  and  scrupu- 
lously cleaned  bottle  is  first  weighed  on  a  chemical  bal- 
ance. The  bottle  is  then  filled  with  recently-boiled  dis- 
tilled water  of  a  temperature  below  60°  F.  (15.5°  C.)  ; 
the  thermometer  is  inserted,  and  the  bottle  is  warmed 
slightly  by  immersing  it  for  a  moment  in  tepid  water 
and  left  standing  until  the  thermometer  shows  60°  F. ; 
the  opening  of  the  side  tube  is  then  wiped  off  and  closed 
with  the  stopper,  and  the  water  on  the  outside  of  the 
bottle  and  in  the  groove  between  its  neck  and  the  ther- 
mometer is  wiped  off  with  filter  paper  or  a  clean  hand 
kerchief,  when  the  bottle  is  again  weighed.  The  weight 
being  recorded,  the  bottle  is  emptied  and  dried  in  a 
water  oven,  or  if  sufficient  milk  is  at  hand,  the  bottle  is 
repeatedly  rinsed  with  the  milk,  the  specific  gravity  of 
which  is  to  be  determined.  It  is  then  filled  with  mill? 
in  a  similar  manner  as  in  case  of  water;  the  tempera 
ture  of  the  milk  should  be  slightly  below  60°  F.  and  is 
slowly  brought  up  to  this  degree  after  the  bottle  has 
been  filled,  proceeding  in  the  same  way  as  before  with 
water;  the  weight  of  the  bottle  and  milk  is  then  taken 
The  weights  of  water  and  of  milk  contained  in  the 
specific-gravity  bottle  are  found  by  subtracting  the 
weight  of  the  empty  bottle  from  the  second  and  the 
third  weights,  respectively,  and  the  specific  gravity  of 


Chemical  Analysis  of  Milk  and  Its  Products.    239 

the  milk  then  found  by  dividing  the  weight  of  the  milk 
by  that  of  the  water. 

Example:     Weight  of  Bp.  gr.  bottle-f  water . .  .146.9113  grams. 
Weight  of  sp.  gr.  bottle  empty. . .  46.9423  grams. 


Weight    of   water 99.9690  grams. 

Weight  of  sp.  gr.  bottle+milk 149.8708  grams. 

Weight  of  sp.  gr.  bottle  empty...  46.9423  grams. 

Weight    of    milk 102.9285  grams. 

Sp.  gr.  of  mite  1-||||p  =1.0296. 

249.  If  a  plain  picnometer  without  a  thermometer  attached 
is  available,  the  method  of  procedure  is  similar  to  that  described, 
with  the  difference  that  the  temperature  of  the  water  and  of  the 
milk  must  be  brought  to  60°  F.  before  the  picnometer  is  filled, 
or  the  picnometer  filled  with  either  liquid  is  placed  in  water  in  a 
small  beaker,  which  is  very  slowly  warmed  to  60°  F.  and  kept  at 
this  temperature  for  some  time  so  as  to  allow  the  liquid  in  the 
picnometer  to  reach  the  temperature  desired;  the  temperature 
of  the  water  in  the  beaker  is  as  ertained  by  means  of  an  accu- 
rate chemical  thermometer.  The  perforated  stopper  is  then 
wiped  off,  the  picnometer  is  taken  out  of  the  water,  wiped  and 
weighed.  It  is  necessary  to  weigh  very  quickly  if  the  room 
temperature  is  much  above  60°  F.,  as  in  such  cases  the  ex- 
panding liquid  will  flow  on  to  the  balance  pan,  with  a  result- 
ant loss  in  weight  from  evaporation. 

The  weights  of  specific-gravity  bottle  or  picnometer,  empty 
and  filled  with  water,  need  only  be  determined  a  couple  of  times, 
and  the  averages  of  these  weighings  are  used  in  subsequent  de- 
terminations. 

250.  Westphal  balance.  Where  only  a  small  amount 
of  milk  is  available,  or  in  rapid  work,  the  specific  grav- 
ity may  be  taken  with  considerable  accuracy  by  means 
of  a  Westphal  balance.  The  arrangement  and  use  of 
this  convenient  little  apparatus  is  readily  explained 
verbally. 


220  Testing  Milk  and  Its  Products. 

For  the  determination  of  the  specific  gravity  of  lop- 
pered  milk,  see  263. 

251.  b.  Water.  The  milk  is  weighed  into  a  perfor- 
ated copper  tube  filled  with  prepared  dry  asbestos.  The 
tubes  are  made  from  perforated  sheet  copper,  with  holes 
about  .7  mm.  in  diameter  and  about  .7  mm.  apart;  they 
are  60  mm.  long,  25  mm.  in  diameter  and  closed  at  the 
bottom.  The  asbestos  is  prepared  from  clean  fibrous 
asbestos,  which  is  ignited  at  low  heat  in  a  muffle  oven, 
treated  with  a  little  dilute  HC1  (1:3)  and  then  with 
distilled  water  till  all  acid  is  washed  out;  it  is  then 
torn  in  loose  layers  and  dried  at  a  low  temperature  in 
an  air  bath ;  when  dry  it  can  be  easily  shredded  in  fine 
strings,  and  is  placed  in  a  wide-mouth,  glass-stoppered 
bottle. 

About  two  grams  of  asbestos  are  placed  in  each  tube, 
packing  it  rather  loosely;  the  tnbe  is  then  weighed,  a 
small  narrow  beaker  being  inverted  over  it  on  the  scale 
pan.  5  cc.  of  milk  are  now  dropped  on  to  the  asbestos 
from  a  5  cc.  fixed  pipette,  the  b«  aker  again  placed  over 
the  tube,  and  the  weight  of  the  5  cc.  of  milk  delivered 
-{-copper  tube  taken.  The  weight  of  the  milk  is  ob- 
tained by  difference.  The  tubes  are  then  placed  in  a 
steam  oven  and  heated  at  100°  C.  until  they  no  longer 
decrease  in  weight,  which  will  ordinarily  take  about 
three  hours.  Place  in  a  desiccator  until  cold,  and  weigh ; 
the  difference  between  the  weight  of  the  tube-j-milk  and 
this  last  weight  gives  the  water  contained  in  the  milk, 
which  is  then  calculated  in  per  cent,  of  the  quantity  of 
milk  weighed  out. 


Chemical  Analysis  of  Milk  and  Its  Products.    221 

Example:     Weight   of   tube+beaker+milk 29.3004  grams. 

Weight  of   tube+beaker 24.1772  grams. 


Milk    weighed    out 5.1232  grams. 

Weight   of   tube+beaker+milk 29.3004  grams. 

Weight    of    tube+beaker+milk,dry  24.9257  grams. 


Weight   of    water 4.3747  grams. 

Per  cent,  of  water  in  milk=  4'*™^°°  =85.39  per  cent. 

Note.  The  per  cent,  of  total  solids  in  milk  is  often 
given,  instead  of  that  of  water;  this  may  be  readily  ob- 
tained by  subtracting  the  weight  of  the  empty  tube 
from  that  of  the  tube  filled  with  milk  solids,  and  finding 
the  per  cent,  of  the  milk  weighed  out  which  this  differ- 
ence makes.  In  the  above  example,  the  weight  of  milk 
solids  thus  is  24.9257— 24.1772=.7485  gram,  and  the 
per  cent,  of  total  solids  in  the  milk=H.61  per  cent. 

252.  Alternate  method.     Five  cc.  of  milk  are  measured  out 
on  a  weighed  flat  porcelain  dish  (50-60  mm.  in  diameter;  porce- 
lain covers  will  answer  the  purpose  well  if  the  handle  be  broken 
off  or  ground  off  level  on  an  emery  wheel) ;  this  is  weighed  rap- 
idly; two  or  three  drops  of  30  per  cent.-acetic  acid  are  added, 
and  the  dish  is  dried  in  a  steam  oven  at  100°  C.  until  no  further 
loss  in  weight  occurs.     After  cooling  in  a  desiccator,  the  weight 
of  the  milk  solids  is  obtained,  and  by  calculation  as  before,  the 
per  cent,  of  water  or  total  solids  in  the  milk. 

253.  c.  Fat.     The  dried  tubes  from  the  water  deter- 
mination are   placed  in  Caldwell   extractors  and  con- 
nected with  weighed,  numbered  glass  flasks   (capacity, 
2-3  oz.)  ;  the  extractors  are  attached  to  upright  Liebig 
condensers  and  the  tubes  extracted  with  pure  ether, 
free  from  water,  alcohol  or  acid,  until  all  fat  is  dis- 
solved;  4-5   hours'   extraction    is    sufficient   for  whole 
milk;  in  case  of  samples  of  skim  milk  it  is  well  to  con- 


222  Testing  Milk  and  Its  Products. 

tinue  the  extraction  for  8  hours.     The  ether  is  then  re- 
covered by  distillation,  and  the  flasks  dried  in  a  steam 
oven    until    constant    weight;    after    cooling    they    are 
weighed  and  the  amount  of  fat  contained  in  the  quan- 
tity of  milk  originally  weighed  into  the  tubes  is  thus 
ascertained,  and  the  per  cent,  present  in  the  milk  cal- 
culated. 
Example:    Weight  of   flask-ffat  .............  15.8039  grams. 

Weight   of   flask  .................  15.5171  grama. 

Weight  of  fat  ...............  2868  gram. 

Milk    weighed   out  ...............     5.1232  grams. 


Per  cent,  of  fat  in  milk=  =5.60  per  cent. 

254.  The  Gottlieb  method  for  the  determination 
of  fat.1  10  cc.  of  milk  are  measured  into  a  glass  cyl- 
inder, %  inch  in  diameter  and  about  14  inches  long  (a 
100  cc.  burette  or  a  Eudiometer  tube  will  do)  ;  1  cc. 
cone,  ammonia  is  added  and  mixed  thoroughly  with  the 
milk;  the  following  chemicals  are  next  added  in  the 
order  given:  10  cc.  of  92  per  cent,  alcohol,  25  cc.  of 
washed  ether,  and  25  cc.  petroleum  ether  (boiling  pt., 
below  80°  C.),  the  cylinder  being  closed  with  a  moist- 
ened cork  stopper  and  the  contents  shaken  several  times 
after  the  addition  of  each  chemical.  The  cylinder  is  then 
left  standing  for  six  hours  or  more.  The  clear  fat  solution 
is  next  pipetted  off  into  a  small  weighed  flask,  by  means 
of  a  siphon  drawn  to  a  fine  point  (see  fig.  6,  loc.  cit), 
which  is  lowered  into  the  fat  solution  to  within  y2  cm. 
of  the  turbid  bottom  layer.  After  evaporating  the  ether 
solution  in  a  hood,  the  flasks  are  dried  in  a  steam  oven 

1  Landw.  Vers.  Sta.,  40  (1892),  pp.  1-27.  The  method  is  also  spoken  of 
as  the  Roese-Gottlieb  method.  The  Mojonnier  tester  (108)  is 
based  on  this  method  and  is  largely  used  in  milk-condensing 
factories  for  determining  solids  and  butter  fat  in  condensed 
milk  and  other  dairy  products. 


Chemical  Analysis  of  Milk  and  Its  Products.    223 

for  two  to  three  hours,  and  weighed.  This  method  is 
applicable  to  new  milk,  skim  milk,  butter  milk,  whey, 
cream,  cheese,  condensed  milk  and  milk  powder,  but  has 
been  found  of  special  value  for  determining  fat  in  skim 
milk,  butter  milk,  cheese,  and  condensed  milk.  In  the 
case  of  products  high  in  fat,  a  second  treatment  with 
10  cc.  each  of  ether  and  petroleum  is  advisable  in  order 
to  recover  the  last  traces  of  fat. 

255.  d.  Casein  and  albumen.  The  sum  of  these  com 
ponents  is  generally  determined  by  the  Kjeldahl 
method.1  5  cc.  of  milk  are  measured  carefully  into  a 
800  cc.  Jena  flask,  20  cc.  of  concentrated  sul- 
furic  acid  (C.  P. ;  sp.  gr.,  1.84)  are  added,  and  .7  gram 
of  mercuric  oxid  (or  its  equivalent  in  metallic  mer- 
cury) ;  the  mixture  is  then  heated  over  direct  flame 
until  it  is  straw-colored  or  perfectly  white ;  a  few  crys- 
tals of  potassium  permanganate  are  now  added  till  the 
color  of  the  liquid  remains  green.  All  the  nitrogen  in 
the  milk  has  then  been  converted  into  the  form  of  am- 
monium sulfate.  After  cooling,  200  cc.  of  ammonia- 
free  distilled  water  are  added,  20  cc.  of  a  solution  of 
potassium  sulfid  (containing  40  grams  sulfid  per  liter) , 
and  a  fraction  of  a  gram  of  powdered  zinc.  A  quan- 
tity of  semi-normal  HCl-solution,  more  than  sufficient 
to  neutralize  the  ammonia  obtained  in  the  oxidation  of 
the  nitrogen  in  the  milk,  is  now  carefully  measured  out 
from  a  delicate  burette  (divided  into  -L  cc.)  into  a  re- 
ceiving flask  and  the  flask  connected  with  a  distillation 
apparatus.  At  the  other  end,  the  Jena  flask  containing 

'Fresenius'  Zeltschrlft,  22,  p.  366;  TT.  S.  Bept.  Apr.  Bur.  of  Chom  . 
Rull.   107,   p.   5. 


224  Testing  Milk  and  Its  Products. 

the  watery  solution  of  ammonia  sulfate  is  connected, 
after  adding  50  cc.  of  a  concentrated  soda  solution  (1 
pound  "pure  potash"  dissolved  in  500  cc.  of  distilled 
water  and  allowed  to  settle)  ;  the  contents  of  the  Jena 
flasks  are  now  mixed  and  heated  to  boiling,  and  the 
distillation  is  continued  for  forty  minutes  to  an  hour, 
until  all  ammonia  has  been  distilled  over. 

The  excess  of  acid  in  the  Erlenmeyer  receiving-flask 
is  then  accurately  titrated  back  by  means  of  a  tenth- 
normal  standard  ammonia-solution,  using  a  cochineal- 
solution1  as  an  indicator.  From  the  amount  of  acid 
used,  the  per  cent,  of  nitrogen  is  obtained;  and  from  it, 
the  per  cent,  of  casein  and  albumen  in  the  milk  by  mul- 
tiplying by  6.25.2  The  amount  of  nitrogen  contained  in 
the  chemicals  used  is  determined  by  blank  experiments 
and  deducted  from  the  nitrogen  obtained  as  described. 

Example:  The  weight  of  5  cc.  of  milk  (as  obtained  in  deter- 
mining the  water  in  the  milk)  was  5.1465  grams.  5  cc.  of  stand 

ard   HC1   are  added   to  the  receiver,   and    1.55   cc.  of  Jl    alkali 

N 
solution  are  used  in  titrating  back  the  excess  of  acid.     1.55  cc. 

of  ~  alkali  =  l~  =.51  cc. -^-acid  solution;  the  ammonia  dis- 
tilled over  therefore  neutralized  5.00 — .31=4.69  cc.  acid.  By 
blank  trials  it  was  found  that  the  reagents  used  furnished  an 
equivalent  of  .02  cc.  acid  in  the  distillate;  this  quantity  sub- 
tracted from  the  acid-equivalent  of  the  nitrogen  of  the  milk 
leaves  4.67  cc.  I  cc.  semi-normal  HCl-solution  corresponds  to 
7  milligrams  or  .007  gram  of  nitrogen;  4.67  cc.  —  HC1  therefore 

represents  .-Q3269  gram  of  nitrogen.  This  quantity  of  nitrogen 
was  obtained  from  the  5.1465  grams  of  milk  measured  out;  the 
milk  therefore  contains  •°^26^x_100  —  .535  per  cent.  Of  nitrogen,  and 
.635X6.25=3.97  per  cent,  of  casein  and  albumen. 

1  Sutton,    Volumetric    Analysis,    4th    edition,    p.    31. 
1  The  factor  6.30  or  6.37  is  more  correct  for  the  albuminoids  of  milk, 
hut  has  not  yet  been  generally  adopted   (p.  15,  foot  note). 


Chemical  Analysis  of  Milk  and  Its  Products.    225 

256.  Casein  and  albumen  may  be  determined  sepa- 
rately by  Van  Slyke's  method;1  10  grams  of  milk  are 
weighed  out  and  diluted  with  about  90  cc.  of  water  at 
40°-42°  C.     1.5  cc.  of  a  10  per  cent,  acetic-acid  solution 
are  then  added ;  the  mixture  is  well  stirred  with  a  glass 
rod  and  the  precipitate  allowed  to  settle  for  3  to  5  min- 
utes.    The  whey  is  decanted  through  a  filter  and  the 
precipitate  washed  two  or  three  times  with  cold  water. 
The  nitrogen  is  determined  in  the  filter  paper  and  its 
contents  by  the  Kjeldahl  method ;  blank  determinations 
with  the  regular  quantities  of  chemicals  and  the s  filter 
paper  used  are  made,  and  the  nitrogen  found  therein 
deducted.     The   per  cent,   of  nitrogen  obtained  multi- 
plied by  6.25  gives  the  per  cent,  of  casein  in  the  milk. 

257.  Albumen  is  determined  in  the  filtrate  from  the 
casein-precipitate;  the  filtrate  is  placed  on  a  water  bath 
and    heated    to   boiling   for   a    period   of   from    ten    to 
fifteen  minutes.     The  washed  precipitate  is  then  treated 
by  the  Kjeldahl  method  for  the  determination  of  nitro- 
gen ;  the  amount  of  nitrogen  multiplied  by  6.25  gives 
the  amount  of  albumen  in  the  milk.     The  difference  be- 
tween the  total  nitrogenous  components  found  by  the 
Kjeldahl  method,  and  the  sum  of  the  casein  and  the 
albumen,  as  given  above,  is  due  to  the  presence  in  milk 
of  a  third  class  of  nitrogen  compounds  (18). 2 

2573.  The  protein  of  milk  may  also  be  obtained  by 
calculation  from  the  total  solids  of  the  milk  by  the  use 
of  the  following  formula  worked  out  by  Mr.  Geo.  A. 

1  Bulletin  107,  p.  117,  Bur.  of  Chem.,  U.  S.  Dept.  of  Agriculture. 

2  Volumetric   determinations   of   casein    in   milk   have   been    proposed 
by  Van  Slyke  and  Bosworth   (Geneva,  N.  Y.)   expt.  station,  tech.  bull. 
10)    and   by   Hart    (Wls.   expt.   station,   research   bull.   11). 

15 


2i!6  Testing  Milk  and  Its  Products. 

Olson1 :  P=T—  JL  The  results  obtained  by  this 
formula  are  quite  satisfactory.'  If  we  assume  that  .8 
of  the  milk  protein  is  casein,  this  component  can  also  be 
obtained  from  the  solids  of  the  milk  by  a  simple  calcula- 
tion by  the  use  of  the  preceding  formula. 

258.  Hart's  test  for  casein  in  milk.      The  following 
test  for  casein  in  milk  has  been  published  by  the  Wis- 
consin experiment  station.2 

Two  cc.  of  chloroform,  20  cc.  of  a  .25  per  cent,  solu- 
tion of  acetic  acid,  and  5  cc.  of  milk  (both  these  latter 
of  a  temperature  of  about  70°  F.)  are  measured  into 
small  tubes  of  special  construction  holding  about  35  cc., 
the  lower  ends  of  which  are  narrow  and  graduated  to 
.1  cc.  The  mixture  is  shaken  for  10  to  20  seconds  and 
the  tubes  then  whirled  iy2' or  8  minutes  in  a  centri- 
fuge of  15  inches  diameter,  making  2000  revolutions  per 
minute.  (The  use  of  a  metronome  is  recommended  to 
facilitate  the  control  of  the  speed.)  After  whirling, 
the  tubes  are  taken  out  of  the  centrifuge  and  allowed 
to  stand  for  10  minutes,  and  the  percentage  of  casein 
read  off  directly  from  the  scale  on  the  lower  end  of  the 
tubes,  each  division  of  which  represents  .2  per  cent,  of 
casein  when  5  cc.  of  milk  are  measured  out.  The  test 
calls  for  considerable  nicety  of  manipulation,  but  ap- 
pears to  give  reliable  results  when  the  directions  given 
are  strictly  followed.8 

259.  e.  Milk  sugar  is  generally  determined  by  differ- 
ence, the  sum  of  fat,  casein  and  albumen  (total  NX6.25) , 

1  .Tourn.   Ind.  and  Eng.   Chemistry,  I.  1909,  p.   253. 

*  Report  24,  p.  117:     "A  simple  method  for  the  estimation  of  casein 
in  cow's  milk." 

*  See  also  Clrc.  10.  Wis.  expt.  sta..  Operating  the  casein  tost  at  cheese 
factories. 


Chemical  Analysis  of  Milk  and  Its  Products.    227 

and  ash,  being  subtracted  from  the  total  solids.  It  may 
be  determined  directly  by  means  of  a  polariscope,  or 
gravimetrically  by  Fehling's  solution;  only  the  former 
method,  as  worked  out  by  Wiley,1  will  be  given  here. 

The  specific  gravity  of  the  milk  is  accurately  deter- 
mined, and  the  following  quantities  of  milk  are  meas- 
ured out  by  means  of  a  100  cc.  pipette  graduated  to  .2 
cc.  (or  a  64  cc.  pipette  made  especially  for  this  purpose, 
with  marks  on  the  stem  between  63.7  and  64.3  cc.),  ac- 
cording to  the  specific  gravities  given:  1.026,  64.3  cc.; 
1.028,  64.15  cc.;  1.030,  64.0  cc.;  1.032,  63.9  cc.;  1.034, 
63.8  cc.;  1.036,  63.7  cc.  These  quantities  refer  to  the 
Schmidt-Haensch  half-shadow  polariscopes,  standard- 
ized for  a  normal  weight  of  26.048  grams  of  sugar.  The 
milk  is  measured  into  a  small  flask  graduated  at  100  cc. 
and  102.6  cc.;  30  cc.  of  mercuric-iodid  solution  (pre- 
pared from  33.2  grams  potassium  iodid,  13.5  grams  mer- 
curic chlorid,  20  cc.  glacial  acetic  acid  and  640  cc. 
water)  are  added;  the  flask  is  filled  to  102.6  cc.  mark 
with  distilled  water,  the  contents  mixed,  filtered  through 
a  dry  filter,  and  when  the  filtrate  is  perfectly  clear,  the 
solution  is  polarized  in  a  200  millimeter  tube.  The 
reading  of  the  scale  divided  by  2,  shows  the  per  cent, 
of  lactose  (milk  sugar)  in  the  milk.  Take  five  readings 
of  two  different  portions  of  the  filtrate,  and  average 
the  results. 

260.  f.  Ash.  About  20  cc.  of  milk  are  measured  into 
a  flat-bottom  porcelain  dish  and  weighed ;  about  one-half 
of  a  cc.  of  30  per  cent-acetic  acid  is  added,  and  the 
milk  first  dried  on  water  bath  and  then  ignited  in  a 

1  Agricultural  Analysis.  III.  p.  275:  Am.  Cbem.  Jour,  6,  p.  289  et  seq. 


228  Testing  Milk  and  Its  Products. 

muffle  oven  at  a  low  red  heat.  Direct  heat  should  not 
be  applied  in  determining  the  ash  in  milk,  since  alkali 
chic  rids  are  likely  to  be  lost  at  the  temperature  to  which 
milk  solids  have  to  be  heated  to  ignite  all  organic  carbon 

Example:     Weight  of  porcelain   dish+milk 49.0907  grams. 

Weight  of   porcelain   dish 28.3538  grams. 


Weight    of    milk 20.7369  grams 

Weight  of  dish+milk,  after  ignition  28.5037  grama 
Weight   of    dish 28.3538  grams. 


Weight  of  milk  ash 1499  gram 

Per  cent,  of  ash=  '-~~  —.72  per  cent. 

The  residue  from  the  determination  of  solids  by  the 
Alternate  Method  given  (252)  may  also  be  used  for  the 
ash  determination. 

B.— CREAM,  SKIM  MILK,  BUTTER  MILK,  WHEY,  CON- 
DENSED MILK. 

262.  The  analysis  of  these  products  is  conducted  in 
the  same  manner  as  in  case  of  whole  milk,  and  the  same 
constituents  are  determined,  when  a  complete  analysis 
is  wanted.  Skim  milk,  butter  milk,  and  whey  con- 
tain relatively  small  quantities  of  solids,  and  espe- 
cially of  fat,  and  it  is,  therefore,  well  to  weigh  out  a 
larger  quantity  than  in  case  of  whole  milk ;  if  possible, 
toward  10  grams.  The  acidity  of  sour  milk  and  butter 
milk  must  be  neutralized  with  sodium  carbonate  pre- 
vious to  the  drying  and  extraction,  as  lactic  acid  is  solu- 
ble in  ether  and  would  thus  tend  to  increase  the  ether- 
extract  (fat),  if  not  combined  with  an  alkali  previous 
to  the  extraction. 


Chemical  Analysis  of  Milk  and  Its  Products.    229 

263.  Specific  gravity  of  butter  milk.  The  specific  gravity 
of  butter  milk  (as  well  as  of  sour  or  loppered  milk)  is  deter- 
mined by  Weibull's  method;  a  known  volume  of  the  ""Ik  ia 
mixed  with  a  certain  amount  (say  10  per  cent.)  of  ammonia  of 
a  definite  specific  gravity,  and  the  specific  gravity  of  the  liquid 
determined  after  thorough  mixing  and  subsequent  standing  for 
an  hour.  If  A  designate  the  volume  of  butter  milk  taken,  B  that 
of  ammonia,  and  C  that  of  the  mixture;  and  if  furthermore  S 
designate  the  specific  gravity  of  the  butter  milk,  *a  that  of  the 
ammonia,  and  *,  that  of  the  mixture,  we  have 

Cs2  -  Bs! 


Klein1  has  modified  this  method  by  weighing  the  liquids,  thus 
securing  greater  accuracy;  22  to  24  per  cent. -ammonia  is  used, 
one-tenth  as  much  being  taken  as  the  amount  of  milk  weighed 
out.  The  results  come  uniformly  .0005  too  high,  and  this  correc- 
tion should  always  be  made.  The  following  formula  will  give 
the  specific  gravity  of  the  milk,  which  in  case  of  careful  work 
will  be  accurate  to  one-half  lactometer  degree;  if  the  letters 
given  above  designate  weights  (instead  of  volumes  as  before) 
and  specific  gravities  of  the  liquids,  respectively,  we  have 

S-     ^; 


Sj    -    Si 

264.  Condensed  milk.  The  same  methods  are,  in  gen- 
eral, followed  in  the  analysis  of  condensed  milk  as  with 
whole  milk.  Condensed  milk  is  preferably  diluted  with 
five  times  its  weight  of  water  prior  to  the  analysis,  both 
because  such  a  solution  can  be  more  easily  handled 
than  the  undiluted  thick  condensed  milk,  and  the  errors 
of  analysis  are  thereby  reduced,  and  because  the  fat  is 
not  readily  extracted  except  when  the  milk  has  been 

1  Milch zeitung,  1896,  p.  656 ;  see  also  De  Koningh,  Analyst,  1899, 
p.  142. 


230  Testing  Milk,  and  Its  Products. 

diluted.1  The  same  constituents  are  determined  as  in 
case  of  whole  milk,  viz.,  solids,  fat,  casein  and  albumen, 
ash,  milk  sugar,  and  cane  sugar  (if  any  has  been  added 
to  the  milk).  The  cane  sugar  is  determined  by  the  dif- 
ference between  the  solids  not  fat  and  the  sum  of  the 
casein,  albumen,  milk  sugar  and  ash ;  if  the  student  has 
a  knowledge  of  the  manipulation  of  the  polariscope  and 
has  had  experience  in  gravimetric  sugar  analysis,  the 
milk  sugar  is  determined  gravimetrically,  and  the  cane 
sugar  by  the  difference  between  the  polariscope  reading 
after  inversion  and  the  milk  sugar  present. 

The  specific  gravity  of  condensed  mUk  may  be  deter 
mined  by  a  method  similar  to  that  of  McGill.2  50  gr. 
of  the  thoroughly  mixed  sample  are  weighed  into  a 
tared  beaker  and  washed  with  warm  water  into  a  250  cc 
flask,  cooled  to  60°,  filled  to  the  mark  and  carefully 
mixed.  The  specific  gravity  of  this  solution  (a)  is  then 
taken  and  the  original  density  is  calculated  by  means 
of  the  following  formula: 

Sp.  gr.  of  condensed  milk=    1 

6— 5a 

Concentration.     The  extent  of  concentration  of  con- 
densed milk  may  be  determined  approximately  by  the 
formula  devised  by  McGill  (loc.  cit.) : 
Concentration  (c)=  -1L_ 

where  a  and  s  designate  the  solids  not  fat  and  specific 
gravity,  respectively,  of  the  condensed  milk,  and  aa  and 
sl  the  corresponding  data  for  the  milk  used.  If  s,= 

*A  second  extraction  following  leaching  and  subsequent  drying  of 
the  tubes  Is  necessary  to  extract  all  the  fat  In  condensed  milk ;  se* 
Bull.  104,  Bur.  of  Chem.,  U.  S.  Dept.  of  Agr.,  p.  102  and  154. 

•Bulletin  54,  Laboratory  Inland  Rev.  Dept.,  Ottawa,  Canada. 


Chemical  Analysis  of  Milk  and  Its  Products.    231 

1.030  and  ai=9  per  cent.,  then  c=—  gives  the  con- 
centration. 

C.—  BtJTTER. 

265.  Sampling.     A   four-  to   eight-ounce  sample   of 
butter   is   melted    in   a  tightly-closed    pint    fruit  jar, 
shaken  vigorously  and  cooled  until  the  butter  is  hard-' 
ened,  the  jar  being  shaken  vigorously  at  short  intervals 
during  the  cooling  so  as  to  keep  the  water  of  the  butter 
evenly  distributed  in  the  mass  (102). 

266.  a.  Determination   of   water.     Small    pieces   of 
butter  (about  2  grams  in  all)  are  taken  from  the  sam- 
ple by  means  of  a  steel  spatula  and  placed  in  glass  tubes, 
seven-eighths  of  an  inch  in  diameter  and  two  and  a  half 
inches  long,  closed  at  the  bottom  by  a  layer  of  stringy 
asbestos,  and  filled  two-thirds  full  of  asbestos  prepared 
as  for  milk  analysis    (252).     The   tubes   are  dried  at 
100°  C.  in  a  steam  oven,  until  no  further  loss  in  weight 
takes  place,  and  are  then  cooled  and  weighed.     The  loss 
in  weight  shows  the  per  cent,  of  water  present. 

267.  b.  Fat.     The  tubes  are  placed  in  Caldwell  ex- 
tractors and  extracted  for  four  hours  with  anhydrous 
ether ;  the  ether  is  then  distilled  off,  and  the  flasks  dried 
in  the  steam  bath  and  weighed,  the  increase  in  weight 
giving  the  fat  in  the  sample  of  butter  weighed  out. 

268.  c.  Casein.    10  grams  of  butter  are  weighed  into 
a  small  beaker  provided  with  a  lip,  and  treated  twice 
with  about  50  cc.  of  gasoline  each  time;  the  solution  is 
filtered  off,  and  the  residue  transferred  to  a  filter  and 
dried;  its  nitrogen  content  is  then  determined  by  the 
Kjeldahl  method  (255).     The  nitrogen  in  the  filter  and 


232  Testing  Milk  and  Its  Products. 

the  chemicals  used  is  determined  by  blank  trials  and 
deducted.  The  nitrogen  multiplied  by  6.25  gives  the 
casein  in  the  butter. 

269.  d.  Ash.     (1)    10  grams  of  butter  are  weighed 
into  a  porcelain  dish  and  treated  twice  with  gasoline,  as 
in  the  preceding  determination;  the  solution  is  filtered 
through  an  ash-free  (quantitative)  filter,  and  the  filter 
when  dry  is  transferred  to  the  dish.     The  dish  is  heated 
in  an  air-bath  for  half  an  hour  and  then  placed  in  a 
muffle  oven,  where  the  contents  are  burnt  to  a  light 
grayish  ash ;  the  dish  is  now  cooled  in  a  desiccator  and 
weighed.     The  difference  between  this  weight  and  that 
of  the  empty  dish  gives  the  amount  of  ash  in  the  butter 
weighed  out. 

270.  (2)    About  two  grams  of   butter  are  weighed  into 
a  small  porcelain  dish,  half  filled  with  stringy  asbestos ; 
the  dish  is  dried  for  half  an  hour  in  the  water  oven, 
and  the  fat  then  ignited  with  a  match,   the  asbestos 
fibre  serving  as  a  wick.     When  the  flame  has  gone  out. 
the  dish  is  placed  in  a  muffle  oven,  and  the  residue 
carefully  burnt  to  a  grayish  ash.    After  cooling,  the  dish 
is  weighed,  and  the  per  cent,  of  ash  in  the  butter  calcu- 
lated as  under  method  1. 

271.  Complete  analysis  of  butter  in  the  same  sam- 
ple.    About  2  grams  of  the  butter  are  weighed  into  a- 
porcelain  gooch  half  filled  with  stringy  asbestos,  and 
dried  in  a  steam  oven  at  100°   C.   to  constant  weight, 
cooled  and  weighed.     The  difference  gives  water  in  the 
sample.     The    gooch   is   then   treated   repeatedly   with 
small  portions  of  gasoline,  suction  being  applied,  and 
again  dried  in  the  water  oven,  cooled,  and  weighed ;  the 


Chemical  Analysis  of  Milk  and  Its  Products.    233 

fat  in  the  sample  is  obtained  from  the  difference  be- 
tween this  and  the  preceding  weight.  The  gooch  is 
then  carefully  heated  at  a  low  red  heat  until  a  light 
grayish  ash  is  obtained;  this  operation  is  preferably 
done  in  a  muffle  oven  to  avoid  a  loss  of  alkali  chlorids. 
The  loss  in  weight  gives  the  casein  in  the  sample 
weighed  out,  and  the  increase  in  the  weight  of  the  gooch 
over  that  of  the  empty  gooch  with  asbestos,  gives  the 
ash  (mainly  salt)  of  the  butter.  The  salt  in  the  ash 
may  be  dissolved  out  by  hot  water,  and  the  chlorin 
content  of  the  solution  determined  by  means  of  a  stand- 
ard silver-nitrate  solution,  using  potassium  chromate  as 
an  indicator  (278). 

272.  Creamery  methods  of  estimating  water  in 
butter.  A  number  of  different  methods  have  been  pro- 
posed of  late  years 
for  the  rapid  esti- 
mation of  water  in 
butter,  the  object 
sought  being  to  en- 
able a  buttermaker 
to  ascertain  the 
water  content  of  his 

butter  without  much          FIG.  58a.     Balance  for  weighing  butter 

trouble  or  delay, 
and  by  using  such  simple  apparatus  as  he  is  likely  to 
have  in  the  creamery  or  can  easily  procure  at  a  low 
price.  The  subject  of  controlling  the  per  cent,  of  water 
in  butter  has  become  more  important  than  was  earlier 
the  case,  through  the  passage  of  the  pure-food  law, 
and  the  promulgation  of  government  food  standards  in 


234  Testing  Milk  and  Its  Products. 

1906  (305)  ;  these  measures  have  rendered  the  question 
of  guarding  against  an  excessive  water  content  in  the 
butter  one  of  the  greatest  importance  to  all  butter- 
makers. 

Most  of  the  methods  suggested  for  this  purpose  are 
essentially  the  common  method  of  chemical  analysis 
modified  to  meet  the  demands  of  every-day  factory  con- 
ditions. References  to 
descriptions  of  the  dif- 
ferent methods  pro- 
posed are  given  below, 
and  a  few  that  are  now 
used  in  factories  and 
outside  of  chemical  lab- 
oratories, are  described 

FIG.  58b.     Scale  for  weighing  but- 
ter for  testing.  in  detail. 

In  all  these  rapid  methods  of  determining  the  water 
content  in  butter,  the  sample  of  butter  must  be  pre- 
pared so  as  to  accurately  represent  the  lot  of  butter 
sampled  (see  102),  and  must  be  carefully  weighed  on  a 
delicate  scale  (see  figures  58a  and  b).  The  directions, 
in  so  far  as  they  are  given  in  detail  in  the  following, 
therefore,  presuppose  that  a  carefully  prepared,  fair 
sample  has  been  obtained  in  all  cases. 

273.  Among  the  methods  proposed  for  the  rapid  de- 
termination of  the  per  cent,  of  water  in  butter  that 
are  adapted  for  use  in  creameries  may  be  mentioned : 

Richmond's  method,1  Carroll's  tester,2  Geldard's  but- 

•  Dairy   Chemistry,    p.    252. 

*Dept.  of  Agr.,  Ottawa,  Dairy  Com'r  Branch,  bull.  6,  pp.  10-11. 


Chemical  Analysis  of  Milk  and  Its  Products.     235 


ter  tester,1  the  Irish  "common  sense  butter  and  cheese 
test,"  Dean's,2  Gray's,3  Patrick's,4  the  Wisconsin  high- 
pressure  oven  method,5  the  Benkendorf  moisture  test,6 
the  Ames  method,7  the  Mitchell- Walker  test,8  and  the 
Cornell  moisture  test-9 

274.  Patrick's  method.  Ten  grams  of  butter  are 
accurately  weighed  into  a  300  cc.  aluminum  beaker 
(about  3  inches  tall  and  2  inches  in  diameter) ;  this  is 
held  by  means  of  a  hand 
clamp  over  the  flame  of 
the  alcohol  lamp  or  a  gas 
burner  .(see  fig.  59)  and 
very  carefully  heated  until 
all  the  water  is  expelled. 
The  beaker  is  then  cooled 
by  sinking  it  to  the  rim  in 
water  of  50°  to  60°,  wiped 
dry,  and  the  loss  in  weight 
calculated  as  water.  If  ten 
grams  of  butter  weighed  J-^%, Aiumujum^gr  and 
8.45  grams  after  heating,  trlck  test- 
the  loss  in  weight  of  1.55  grams  represents  15.5  per 
cent,  of  the  weight  of  the  sample,  and  the  butter  there- 

1  Dept.  of  Agr.,  Ottawa,  Dairy  Com'r  Branch,  bull.  14,  pp.  6-8. 

*  Ontario  Agr.  College,  rept.  1906,  p.  120. 

*  Clrc.  100,  Bur.  An.  Ind.,  U.  S.  Dept.  of  Agr. 
« Journal  Am.  Chem.  Soc.,  28,  1906,  p.  1611. 
•Bull.   154,   Wis.   exp.   sta. 

•Bull.  220,  Wis.  exp.  sta. 

TBull.  97,  Iowa  exp.  sta. 

•Bull.  167,  Dairy  Branch,  Ont.  Dept.  of  Agr. 

•Bull.   281,  Cornell  exp.   sta. 


236  Testing  Milk  and  Its  Products. 

fore  contained  15.5  per  cent,  of  water.-  The  results  ob- 
tained by  this  method  seldom  vary  more  than  .2  per 
cent,  from  those  of  chemical  analysis,  and  often  less 
than  .1  per  cent,  when  proper  care  in  sampling  and 
weighing  has  been  taken. 

A  few  points  need  special  attention  in  using  this 
method:  First,  care  must  be  taken  not  to  heat  the 
beaker  too  fast  so  that  spattering  occurs ;  there  is  not  so 
much  danger  from  this  source  when  an  alcohol  lamp  is 
used  as  with  a  gas  burner,  which  easily  raises  the  tem- 
perature too  high,  causing  a  fine  spray  of -material  to 
be  thrown  about,  and  thus  giving  too  high  results  for 
water  content.  Second,  it  is  important  to  discontinue 
the  heating  at  the  exact  point  when  all  the  water  has 
been  driven  off  and  before  burning  of  the  non-fatty 
solids  (casein,  milk  sugar,  and  organic  acids)  occurs, 
as  indicated  by  a  slight  darkening  in  color.  It  is  not 
necessary  to  cool  the  beakers  in  water,  but  they  can  be 
left  to  cool  in  the  air.  The  determination  of  water  in 
butter  by  this  method  can  be  finished  in  ten  minutes 
or  less  by  an  experienced  operator. 

The  Irish  test  is  similar  to  the  method  described  in 
the  preceding,  differing  from  the  same  mainly  in  the 
shape  of  the  aluminum  dishes  used.  Modifications  of 
this  test  have  also  been  worked  out  by  the  Iowa  and 
Cornell  experiment  stations,  which  are  designed  to  pre- 
vent losses  by  spattering  when  the  dish  is  heated.  In 
the  Ames  method  the  aluminum  dish  containing  the 

*  A  Convenient  table  showing  per  cents  of  moisture  In  butter  direct 
when  9  to  10.15  grams  are  weighed  out,  has  been  published  by  the 
Copenhagen  experiment  station  (62nd  report ;  see  N.  Y.  Produce  Rev.. 
1908,  p.  530). 


Chemical  Analysis  of  Milk  and  Its  Products.    237 

sample  is  heated  with  a  paraffine  bath,  while  in  the  Cor- 
nell test  a  thin  sheet  of  asbestos  is  placed  between  the 
flame  and  the  dish  holding  the  samples. 

275.  Dean's  method.     Three  cc.  of  a  melted  sample 
}f  butter  are  placed  in  an  ordinary  "patty-pan"  tin 
dish   (about  2y2  inches  in  diameter  and  %  inch  deep) 
ind  accurately  weighed;  the  dish  is  then  placed  in  a 
steam  oven  provided  with  a  pop  safety  valve,  a  steam 
pressure   gauge,   and   a  thermometer.     The   oven   used 
by  Professor  Dean   of  Guelph  (Ont.)  Dairy  School,  the 
originator  of  this  method,  was  6x8  inches.     It  was  made 
of  galvanized  iron  by  a  local  tin-smith  at  a  cost  of 
about  $5.00,  exclusive  of  safety  valve  and  steam  gauge, 
and   was  made  to   withstand  a  pressure  of   about   10 
pounds.     After  five  or  six  hours'  drying  in  the  oven, 
the  samples  of  butter  are  ready  to  be  weighed,  and  the 
loss  gives  the  amount  of  water  present  therein.     The 
average  results  obtained  by  this  method  with  nine  sam- 
ples of  butter  came  within  .13  per  cent,  of  those  found 
by  chemical  analyses. 

The  same  method  is  recommended  by  the  author  for 
determining  the  per  cent,  of  water  in  curd  or  cheese. 

276.  The    Wisconsin    high-pressure    oven    method 
(see   fig.  60).      Either   10   or  50  grams'   of  butter   are 
weighed  in  a  flat-bottomed  tin  or  aluminum  dish.     This 
is  placed  in  an  oven  heated  by  high  pressure  steam  to  a 
temperature  of  240°  to  280°  F.    The  length  of  time  re- 
quired to  expel  all  the  water  from  the  butter  will  de- 
pend on  the  temperature  of  the  oven  and  the  diameter 
of  the  dish  in  which  the  butter  is  heated.     If  the  dish 


238 


Testing  Milk  and  Its  Products. 


is  large  enough  to  permit  the  butter  to  spread  into 
a  very  thin  layer  and  the  temperature  of  the  oven 
reaches  260°  F.,  the  water  will  be  completely  expelled 
in  half  an  hour.  Ovens  of  this  construction  have  now 
been  placed  on  the  market  by  manufacturers  of  dairy 
supplies.  A  steam  pressure  of  60  Ibs.  and  a  tempera- 
ture of  280°  F.  may  be  obtained  in  such  an  oven;  by 
employing  the  boiler  pressure  ordinarily  used  in  a 
creamery,  temperatures  of  240°  to  260°  may  be  easily 
obtained.  The  temperature  thus  reached  is  sufficient  to 
dry  the  butter  completely  within  an  hour,  provided 
pans  large  enough  to  spread  the  butter  in  a  thin  layer 
are  used. 

If  10  grams  of  butter  are  used  in  making  tests,  a 
more  delicate  scale  is  necessary  than  when  50  grams 
are  taken.  There  are  other  advantages  in  using  as  large 
a  quantity  as  50  grams  of  butter  for  making  tests  of 
water.  First,  a  sample  can  be 
weighed  out  directly  from  a 
package.  Second,  ordinary  tin 
basins  at  least  5  inches  in 
diameter  can  be  used  for  dry- 
ing the  butter.  Third,  scales 
with  a  graduated  side  beam 
and  sensitive  to  .1  gram  in- 
stead of  those  with  smaller 
loose  weights  can  be  used  for 
weighing  the  butter.  (See  figs. 


\ 


is.    60.     The    Wisconsin      5g(J  and  58e  ) 
high-pressure  oven.  «wo./ 


Chemical  Analysis  of  Milk  and  Its  Products.    239 

277.  TheBenkendorf 
moisture  tester  consists 
of  a  small  cast-iron  oven 
(3l/2x3i/2  inches,  1  inch 
deep)  which  is  heated  by 
an  alcohol  or  gas  lamp. 
A  thin  piece  of  asbestos 
is  placed  on  the  bottom  of 
the  oven.  This  aids  in 
distributing  the  heat  so 
that  the  butter  which  is 
weighed  into  a  shallow, 

_          ,  Fig.   61.  The  Benkendorf  tester. 

fl  a  t-b  o  1 1  o  m   aluminum 

dish,  about  three  inches  in  diameter,  is  heated 
from  above  as  well  as  from  below.  10  grams  of 
butter  are  commonly  used  in  this  test  and  the  moist- 
ure evaporates  in  about  five  to  ten  minutes. 

278.     Creamery  methods  of  estimating  salt  in  butter.     I. 

The  ordinary  volumetric  method  used  in  chemical  laboratories  for 
determining  the  salt  content  of  butter  has  been  adapted  for 
work  in  the  creamery  by  Prof.  Sammis.1  5.1  grams  of  chemically 
pure  nitrate  crystals  are  dissolved  in  250  cc.  of  water.  Each  cc. 
of  this  solution  will  represent  1  per  ct.  of  salt  when  17.6  cc.  of 
the  liquid  are  measured  which  is  obtained  by  shaking  10  grams 
of  butter  with  250  cc.  of  clean,  warm  water.  The  silver  nitrate 
solution  is  added  from  a  25  or  50  cc.  burette  divided  into  tenths 
of  a  cubic  centimeter.  One  or  two  drops  of  the  usual  indicator 
employed  (1  oz.  potassium  chromate  dissolved  in  100  cc.  of  water) 
are  added  prior  to  the  titration. 

II.     The  use  of   silver  nitrate   tablets  for  making  standard 
solutions    for    volumetric    determinations    of    salt    in    butter    \v>is 

'('Ire.  14,  Wisconsin  cxpt.  station. 


240  Testing  Milk  and  Its  Products. 

proposed  by  Prof.  A.  Vivian  and  C.  L.  Fitch  in  1901.1  The  tab- 
lets have  not  been  on  the  market  during  late  years. 

2783.  Shaw 's  test  for  fat  and  salt  in  butter.    R.  H. 

Shaw  has  devised  a  method  for  determining  the  per- 
centages of  fat  and  salt  in  the  same  sample  of  butter 
which  has  considerable  merit.  For  description  of  this 
method  see  Circ.  202,  Bur.  of  Animal  Ind.,  U.  S.  Dept. 
of  Agriculture. 

DETECTION  OF  ARTIFICIAL  BUTTER. 

279.  Determination  of  the  specific  gravity  of  the  fil- 
tered butter  fat  serves  as  a  good  preliminary  test.  A 
number  of  practical  methods  for  the  detection  of  artifi- 
cial butter  have  been  proposed,  but  they  are  either 
worthless  for  the  examination  of  samples  containing  a 
considerable  proportion  of  natural  butter,  or  give  satis- 
factory results  only  in  the  hands  of  experts.  The  Reich- 
ert-Meissl  method  given  in  detail  below  is  the  standard 
method  the  world  over,  and  the  results  obtained  by  it 
are  accepted  in  the  courts. 

280..  Filtering  the  butter  fat.  The  butter  to  be  ex- 
amined is  placed  in  a  small  narrow  beaker  and  kept  at 
60°  C.  for  about  two  hours.  The  clear  supernatant  fat 
is  then  filtered  through  absorbent  cotton  into  a  200  cc. 
Erlenmeyer  flask,  taking  care  that  none  of  the  milky 
lower  portion  of  the  contents  of  the  beaker  be  poured 
on  the  filter.  In  sampling  the  butter  fat,  it  is  poured 
back  and  forth  repeatedly  from  a  small  warm  beaker 
into  the  flask,  and  the  quantity  wanted  is  then  drawn 
off  with  a  warm  pipette. 

1  Wis.  experiment  station,  report  17,  pp.  98-101  :  Hoard's  Dairyman. 
February  15.  1001.  "Uniform  Salting  of  Butter." 


Chemical  Analysis  of  Milk  and  Its  Products.    241 

281.  Specific  gravity.     This  is  generally  determined 
at  100°  C.     The  method  of  procedure  is  similar  to  that 
described  under  milk  (248).     The  picnometer  (capacity 
about  25  cc.)  is  filled  with  dry  filtered  butter  fat,  free 
from  air  bubbles;  the  fat  is  heated  for  30  minutes  in  a 
beaker,  the  water  in  which  is  kept  boiling.     On  cooling, 
the  weight  of  picnometer  and  fat  is  obtained,  and  by 
calculation  as  usual,  the  specific  gravity  of  the  fat. 

The  specific  gravity  of  pure  natural  butter  fat  at 
100°  C.  ranges  between  .8650  and  .8685,  while  artificial 
butter  fat  (i.  e.,  fat  from  other  sources  than  cow's  milk) 
has  a  specific  gravity  at  100°  C.  of  below  .8610,  and  gen- 
erally about  .85. 

282.  Reichert-MeissI  method  (Volatile  Acids.)    5.75 
cc.  of  fat  are  measured  into  a  strong  250  cc.  weighed 
saponification  flask,  by  means  of  a  pipette  marked  to 
deliver  this  amount,  and  the  flask  when  cool  is  weighed 
again.     20  cc.   of  a  glycerol-soda  solution    (20  cc.  of 
soda  solution  (1 : 1)  to  180  cc.  of  pure  glycerol),  are  then 
added  to  the  flask  and  the  flask  is  heated  over  a  naked 
flame  or  hot  asbestos  plate  until  complete  saponification 
has  taken  place,  as  shown  by  the  mixture  becoming  per- 
fectly clear.     If    foaming    occur,  the    flask    is    shaken 
gently-. 

135  cc.  of  recently-boiled  distilled  water  are  now 
added,  drop  by  drop,  at  first,  to  prevent  foaming,  and 
when  the  solution  is  clear,  cooled  to  about  70°  C. ;  5  cc. 
of  dilute  sulfuric  acid  (200  cc.  cone.  H2SO4  per  liter)  are 
added  to  the  soap  solution  to  decompose  the  soap  into 
free  fatty  acids  and  glycerol.  A  few  pieces  of  pumice 
stone  (prepared  by  throwing  the  pieces  at  white  heat 
Lie 


242  Testing  Milk  and  Its  Products. 

into  distilled  water  and  keeping  them  under  water  until 
used)  are  added,  the  flask  connected  with  a  glass  con- 
denser, heated  slowly  till  boiling  begins,  and  the  con- 
tents then  distilled  at  such  a  rate  as  will  bring  110  cc. 
of  the  distillate  over  in  as  nearly  thirty  minutes  as  pos- 
sible. 

The  distillate  is  mixed  thoroughly  and  filtered 
through  a  dry  filter;  100  cc.  of  the  filtrate  are  poured 
into  a  250  cc.  beaker  and  titrated  with  a  deci-normal 
barium-hydrate  solution,  half  a  cubic  centimeter  of  phe- 
nolphtalein  solution  being  used  as  an  indicator.  A  blank 
test  is  made  in  the  same  manner  as  described,  and  the 
amount  of  alkali  solution  used  deducted  from  the  re- 
sults obtained  with  the  samples  analyzed.  The  number 
of  cubic  centimeters  of  barium-hydrate  solution  used  is 
increased  by  one-tenth,  and  thfr  so-called  Reichert  or 
Reichert-Meissl  number  thus  obtained. 

The  Keichert  number  for  pure  butter  fat  will  ordi- 
narily ccme  above  24  cc.  and  may  go  over  30  cc;  butter 
fat  from  stripper  cows  will  have  a  low  Reichert  num- 
ber. Pure  oleomargarine  will  have  a  Reichert  number 
of  1  to  2  cc. ;  and  mixtures  of  artificial  and  natural  but- 
ter will  give  intermediate  numbers. 

TESTS  FOB  THE  DETECTION  OF  OLEOMARGARINE  OB  RENO- 
VATED BUTTER. 

283.  The  boiling  test.1  A  piece  of  butter  of  the  size 
of  a  small  chestnut  is  melted  in  an  ordinary  tablespoon 

1  Pntrirk.  Household  tests  for  the  detection  of  oleomargarine  and 
renovated  butter.  Fanner's  Bulletin.  No.  131.  For  detection  and 
examination  of  renovated  or  "process"  butter,  see  also  Cochran.  Jnurn 
Franl-l.  Inst.,  1899,  p.  94;  Analyst,  1899,  p.  88. 


Chemical  Analysis  of  Milk  and  Its  Products.    243 

(or  a  small  tin  dish)  at  a  low  heat,  stirring  with  a  splin- 
ter of  wood.  The  heat  is  increased  nnf.il  as  brisk  a  boil 
as  possible,  and  after  boiling  has  begun,  the  melted  mass 
is  stirred  thoroughly  two  or  three  times,  always  shortly 
before  boiling  ceases.  Oleomargarine  and  renovated 
butter  will  boil  noisily,  sputtering  like  a  mixture  of 
grease  and  water  when  boiled,  and  will  produce  but 
little  or  no  foam.  Renovated  butter  produces  usually  a 
very  small  amount  of  foam,  while  genuine  butter  boils 
with  less  noise  and  produces  an  abundance  of  foam. 

284.  The  Waterhouse  test  for  distinguishing  oleo- 
margarine and  renovated  butter.1  Half  fill  a  100  cc. 
beaker  with  sweet  skim  milk  (or  distilled  water),  heat 
nearly  to  boiling  and  add  5  to  10  grams  of  butter  or 
oleomargarine.  Stir  with  a  small  wooden  stick  of  about 
the  size  of  a  match  until  the  fat  is  melted ;  the  beaker  is 
then  placed  in  ice  water,  and  the  milk  (or  water)  stirred 
until  the  temperature  falls  sufficiently  for  the  fat  to 
congeal.  If  oleomargarine,  the  fat  can  now  be  easily 
collected  into  one  lump  by  means  of  the  stick,  while  if 
genuine  or  renovated  butter,  the  fat  will  granulate  and 
can  not  be  so  collected.2 


D.- 

For  method  of  sampling,  see  par.  104. 

285.  a.  Water.  Five  grams  of  cheese  cut  into  very 
thin  slices  are  weighed  into  a  small  porcelain  dish  filled 
about  one-third  full  with  freshly-ignited  stringy  asbes- 

1  Farmers'  Bulletin  No.  131,  p.  7. 

»For  tests  for  artificial  coloring  matter  In  oleomargarine,  see  Clrc. 
629,  Com.  of  Internal  Rev.,  Treasury  Dept. 


244  Testing  Milk  and  Its  Products. 

tos ;  the  dish  is  placed  in  a  water  oven  and  heated  for  ten 
hours.  The  loss  in  weight  is  taken  to  represent  water. 
In  cheese  factories  the  Wisconsin  high-pressure  oven 
(276)  is  now  used  for  making  moisture  tests  of  cheese. 
A  10-gram  sample  requires  about  five  hours'  heating 
to  expell  all  the  moisture  in  the  cheese.  The  rapid 
methods  for  moisture  testing  of  butter  do  not  give 
satisfactory  results  with  cheese.1 

286.  b.  Fat.     About  5  grams  of  cheese  are  ground 
finely  in  a  small  porcelain  mortar  with  about  twice  its 
weight  of  anhydrous  copper  sulfate,  until  the  mixture  is 
of  a  uniform  light  blue  color  and  the  cheese  evenly  dis- 
tributed throughout  the  mass.     The  mixture  is  trans- 
ferred to  a  glass  tube  of  the  kind  used  in  butter  analysis 
(263),  only  a  larger  size;  a  little  copper  sulfate  is  placed 
at  the  bottom  of  the  tube,  then  the  mixture  containing 
the  cheese,  and  on  top  of  it  a  little  extracted  absorbent 
cotton  or  ignited  stringy  asbestos ;  the  tube  is  placed  in 
an  extraction  apparatus  and  extracted  with  anhydrous 
ether  for  fifteen  hours.     The  ether  is  then  distilled  off, 
the  flasks  dried  in  a  water  oven  at  100°  C.  to  constant 
weight,  cooled  and  weighed.     The  method  is  apt  to  give 
too  low  results  and,  therefore,  not  to  be  preferred  to 
the  Babcock  test  for  cheese  (105). 

287.  c.  Casein  (total  nitrogenX6.25).  About  2  grams 
of  cheese  are  weighed  out  on  a  watch  glass  and  trans- 
ferred to  a  Jena  nitrogen  flask,  and  the  nitrogen  in  the 
sample  determined  according  to  the  Kjeldahl  method 

1  See  also  Dean's  method  for  determining  water  in  butter, 
curd  and  cheese,  276,  ami  the  Walker  casein  test,  N.  Y.  Produce 
Rejr.  1913,  p.  1154. 


Chemical  Analysis  of  Milk  and  Its  Products.     245 

(253)  ;  the  percentage  of  nitrogen  multiplied  by  6.25 
gives  the  total  nitrogenous  components  of  the  cheese. 

288.  d.  Ash.    The  residue  from  the  water  determina- 
tion is  taken  for  the  ash ;  it  is  preferably  set  fire  to,  in 
the  same  manner  as  explained  under  determination  of 
ash  in  butter   (270),  before  it  is  placed  in  the  muffle 
oven  and  incinerated.     The  increase  in  the  weight  above 
that  of  the  empty  dish-)-asbestos,  gives  the  amount  of 
ash  in  the  sample  weighed  out. 

289.  e.  Other  constituents.    The  sum  of  the  percent- 
ages of  water,  fat,  casein  and  ash,  subtracted  from  100, 
will   give  the  per  cent,   of  other  constituents,  organic 
acids,  milk  sugar,  etc.,  in  the  cheese. 

«, 
DETECTION  OF  OLEOMARGARINE  CHEESE  ("FILLED" 

CHEESE.) 

290.  About  25  grams  of  finely-divided  cheese  are  ex- 
tracted with  ether  in  a  Caldwell  extractor  or  a  paper 
extraction  cartridge;  the  ether  is  distilled  off,  and  the 
fat  dried  in  the  water  oven  until  there  is  no  further 
loss  in  weight.     5.75  cc.  of  the  clear  fat  are  then  meas- 
ured into  a  250  cc.  saponification  flask  and  treated  ac- 
cording to  the  Reich ert-Meissl  method,  as  already  ex- 
plained under  Detection  of  Artificial  Butter  (282). 1 

TESTS  FOR  ADULTERATION  OF  MILK  AND  CREAM. 

291.  Use  of  the  refractometer.     The  immersion  re- 
fractometer  furnishes  a  delicate  apparatus  for  the  de 
tection  of  watered  milk.2    100  cc.  of  milk  and  2  cc.  of 

1  See  Arb.   Kais.   Ges.-Amt.,   14,  506-598. 

1  Leach,  Food  Analysis,  2nd  ed.,  p.  168.     See  also  Jr.  Ind.  and  Eng. 
Chem.,   1911,  p.  44  and  p.  573. 


246  Testing  Milk  and  Its  Products. 

25%  acetic  acid  are  heated  for  twenty  minutes  at  70°  C. 
This  is  then  placed  on  ice  for  ten  minutes  and  filtered. 
The  refractometer  reading  of  the  clear  filtrate  is  then 
taken  at  20°  C.  If  this  reading  is  above  40  the  milk  is 
not  watered,  while  figures  below  40  show  adulteration  by 
watering. 

2913.  The  nitric  acid  test  may  prove  useful  as  cor- 
roborative evidence  that  a  sample  of  milk  has  been 
watered  (126).  Normal  fresh  milk  does  not  contain 
nitrates,  while  common  well-water,  particularly  on 
farms  where  precautions  to  guard  against  contamina- 
tion of  the  water  supply  have  not  been  taken,  in  gen- 
eral contains  appreciable  amounts  of  nitrates,  nitrites 
and  ammonia  compounds,  and  watered  milk  will,  there- 
fore, in  such  cases  also  contain  nitrates.1  The  method 
for  detection  of  small  amounts  of  nitrates  in  milk,  as 
given  by  Richmond2  is  as  follows :  Place  a  small  quan- 
tity of  diphenylamin  at  the  bottom  of  a  porcelain  dish, 
and  add  to  it  about  1  cc.  of  pure  H^SO*  (cone.)  ;  allow 
a  few  drops  of  the  milk  serum  (obtained  by  adding  a 
little  acetic  acid  to  the  milk  and  warming)  to  flow  down 
the  sides  of  the  dish  and  over  the  surface  of  the  acid. 
If  a  blue  color  develops  in  the  course  of  ten  minutes, 
though  it  may  be  faint,  it  shows  the  presence  of  nitrates ; 
after  ten  minutes  a  reddish-brown  color  is  always  de- 
veloped from  the  action  of  the  acid  on  the  serum. 
There  should  be  .no  difficulty  in  detecting  an  addition  of 
10  per  cent,  of  water  to  the  milk  by  this  test,  if  the 
water  added  contained  5  parts  of  nitric  acid,  or  more, 
per  100,000. 

1  Uffelmann,   Deutsche  Vierteljahresschr.   f.   6ff.  Ges.-pfl.,   15,  p.  663. 

2  The  Analyst,  1893,  p.  272. 


Chemical  Analysis  of  Milk  and  Its  Products.    247 

The  following  test  for  nitric  acid  is  proposed  by  Mc- 
Kay and  Bouska:  About  5  cc.  of  milk  is  placed  in  a 
test  tube.  Some  Kaniss'  reagent  (about  1  part  formal- 
dehyd  in  500  cc.  C.  P.  H2SOJ  is  poured  down  the  side 
of  the  tube  so  it  will  form  a  layer  under  the  milk.  If 
nitrates  or  nitrites  are  present,  a  violet  ring  will  form 
at  the  place  of  contact.  This  is  Hehner's  test  for  for- 
maldehyd  reversed,  see  (304). 

292.  Besides  by  the  methods  given  in  the  preceding 
(pp.  121-127),  watering  or  skimming  of  milk  may  be  de- 
tected by  determining  the  specific  gravity  of  a,  the  skim 
milk,  b,  the  milk  serum,  and  c,  the  whey. 

a.  Specific  gravity  of  skim  milk.      The  milk  is  set  in  a  flat 
porcelain  or  glass  dish  for  12  to  24  hours  in  a  cold  room;  the  layer 
of  cream  formed  is  then  skimmed  off,  and  the  sp.  gr.  of  the  skim 
milk  determined  at  60°   F.     Skim  milk  has  a  sp.  gr.  of  .002  to 
.0035  (2  to  3.5  lactometer  degrees)  above  that  of  the  correspond- 
ing whole  milk ;  a  smaller  difference  than  this  indicates  that  the 
milk    was   skimmed.     Tf  both    skimming  and  watering  had  been 
practiced,  the  difference  given  above  might  be  obtained,  but  the 
analysis  of  the  milk  would  in  such  case  easily  disclose  the  adul- 
teration. 

b.  Specific  gravity  of  the  milk  serum.      To  100  ce.  milk  2 
cc.  of  20  per  cent.-acetic  acid  are  added,  and  the  mixture  heated 
in  a  covered  beaker  or  closed  flask  for  5-10  min.  on  a  water-bath 
at  55-65°  C.     After  cooling,  the  milk  serum  is  filtered  off  and  ita 
sp.  gr.  determined  at  60°  F.     In  case  of  pure  milks,  the  sp.  gr. 
of  the  milk  serum  (at  60°)  will  come  above  1.0270.     Serum  from 
normal  milk  contains   6.3   to   7.5   per   cent,   solids   and  .22  to  .28 
per   cent,    fat;    by  the   addition   of   10    per   cent,    of   water,    the 
solids  in  the  serum  are  lowered  .3  to  .5  per  cent.,  and  the  sp.  gr., 
.0005.1 

c.  Specific  gravity  of  whey.    500  cc.  of  milk  are  warmed  iu 
Water  of  40-50°  C.  until  its  temperature  is  35°  C.;   one-half  cc. 
of  rennet  extract   (12-15  drops)   is  added,   and  the  milk  stirred 

1K8nlg,  Menschl.  Nahrungsmittel,  II,  p.  276. 


248  Testing  MUk  and  Its  Products. 

thoroughly.  After  allowing  the  curd  to  solidify  for  10  minutes, 
it  is  cut  and  the  whey  filtered  off  through  several  layers  of  cheese 
cloth.  The  whey  must  be  clear;  it  is  cooled  to  60°  F.  and  its 
sp.  gr.  determined.  The  sp.  gr.  of  whey  from  normal  milk  ob- 
tained in  the  manner  given  will  range  between  1.027  and  1.031. 
A  sp.  gr.  of  1.026  or  below  indicates  watering.  An  addition  of 
4  per  cent,  of  water  lowers  the  sp.  gr.  of  the  whey  about  1  lac- 
tometer degree.2 

293.  Detection  of  coloring  matter.     Milk  which  has 
been  watered  or  skimmed,  or  both,  is  sometimes  further 
adulterated  by  unscrupulous  milk  dealers  by  an  addi- 
tion of  a  small  quantity  of  cheese  color;  this  will  mix 
thoroughly  with  the  milk,  and,  if  added  judiciously,  will 
impart  a  rich  cream  color  to  it.     The  presence  of  for- 
eign coloring  matter  in  milk  is  easily  shown  by  shaking 
10  cc.  of  the  milk  with. an  equal  quantity  of  ether;  on 
standing,  a  clear  ether  solution  will  rise  to  the  surface ; 
if  artificial  coloring  matter  has  been  added  to  the  milk, 
the  solution  will  be  yellow  colored,  the  intensity  of  the 
color   indicating   the    quantity   added;    natural   fresh 
milk  will  give  a  colorless  ether  solution. 

A  method  gived  by  Wallace1  is  claimed  to  detect  one 
part  of  coloring  matter  in  100,000  of  milk. 

Inorganic  coloring  matter  like  chromates  and  bi-chro- 
mates  have,  although  fortunately  rarely,  been  used  to 
impart  a  rich  color  to  adulterated  milk  or  poor  cream. 
Chromates  may  be  detected  by  the  reddish  yellow  color 
produced  when  a  little  2  per  cent.-silver  nitrate  solution 
is  added  to  a  few  cubic  centimeters  of  the  milk. 

294.  Detection  of  pasteurized  milk  or  cream.    Prof. 
Storch,  of  Copenhagen,  Denmark,2  in  1898,  published  a 
simple  method   for  ascertaining   whether  milk,   cream, 

*  Slats,  Unters.  landw.   vrlcht.   Stoffe,  p.  88. 
1  N.  J.  Dairy  Commissioner,  report  1896,  p.  36. 
1  40th  report,  Copenhagen  experiment  station. 


Chemical  Analysis  of  Milk  and  Its  Products.    249 

or  other  dairy  products  have  been  heated  to  at  least 
176°  F.  (80°  C.).  The  test  is  made  as  follows:  A 
teaspoonful  of  the  milk  is  poured  into  a  test  tube,  and 
1  drop  of  a  weak  solution  of  peroxid  of  hydrogen  (2 
per  cent.)  and  2  drops  of  a  paraphenylenediamin-solu- 
tion  (2  per  cent.)  are  added.  The  mixture  is  then 
shaken;  if  a  dark  violet  color  appears  at  once,  the  milk 
has  not  been  heated,  or  at  any  rate  not  beyond  176°  F. 
If  a  sample  of  butter  is  to  be  examined,  25  grams  are 
placed  in  a  small  beaker  and  melted  by  being  placed  in 
water  of  60°  C.  The  clear  butter  fat  is  poured  off,  and 
the  remaining  liquid  is  diluted  with  an  equal  volume  of 
water.  The  mixture  thus  obtained  is  examined  as  in 
case  of  milk. 

Guaiacum  tincture  has  also  been  recommended  for  the 
detection  of  pasteurized  cream  or  milk;  this  solution  is 
easily  obtained,  keeps  well,  and  is  convenient  to  use 
(McKay). 

295.  Boiled  milk.     The  preceding  tests  will  serve  to 
distinguish  between  raw  and  boiled  milk,  and   also  to 
ascertain  if  milk  has  been  adulterated  with  diluted  con- 
densed milk.     To  what  extent  such  an  adulteration  can 
be  practiced  without  being  detected  by  this  or  similar 
tests,  has  not  been  determined,  but  if  a  control  test  be 
made  at  the  same  time  with  a  sample  of  milk  of  known 
purity,  a  small   admixture  of  boiled   (or  diluted   con- 
densed) milk  can  doubtless  be  detected.1 

296.  Gelatine  in   cream.     This  method  of  adultera- 
tion is  sometimes  practiced  in  the  city  cream  trade,  to 
impart  stiffness  and  an  appearance  of  richness  to  the 
cream.     To  detect  the  gelatine,  a  quantity  of  the  sus- 

1  See  also  Slats,  Unters.  landw.  wlcht.  Stoffe,  p.  60,  and  Molkerel- 
Ztg.  (Hlldeshelm),  1899,  p.  677. 


250  Testing  Milk  and  Its  Products. 

pected  cream  is  mixed  with  warm  water,  and  acetic  acid 
is  added  to  precipitate  the  casein  and  fat  (1.5  cc.  of  10 
per  cent.-acetic  acid  per  10  cc.  of  cream  is  sufficient). 
The  precipitate  is  filtered  off,  and  a  few  drops  of  a 
strong  tannin  solution  are  added  to  the  clear  filtrate. 
Pure  cream  will  give  a  slight  precipitate,  while  in  the 
presence  of  gelatine  a  copious  precipitate  will  come 
down. 

The   picric-acid  method  has  also  been    proposed    for 

the  detection  of  small  quantities  of  gelatine  in  cream.1 

297.  Starch  in   cream.     Starch  is  mentioned  in  the 

dairy  literature  as  an  adulterant  of  milk  find  fronm.    Tt 

is  doubtful,  how- 
ever, if  it  is  ever 
used  for  the  pur- 
pose at  the  present 
time.  In  the  case 
of  ice-cream,  on 
the  other  hand,  a 
small  quantity  of 
corn  starch  is 
often  added  to 
thicken  the  milk 
used.  It  may  in 
suchacasebe 
readily  detected  by 
means  of  the  iodin 

FIG.  62.    The  Wisconsin  Milk  Sediment  Test.       reaction.       A    Solu- 

solution  of  iodin  will  produce  a  deep  blue  color  in  the 
presence  of  starch;  a  small  amount  of  iodin  is  taken  up 
by  the  cream  before  the  blue  coloration  appears. 

'The  Analyst,   1897.  p.  .V_>0. 


Chemical  Analysis  of  Milk  and  Its  Products.       251 

298.  Macroscopic  impurities  (particles  of  hay,  litter, 
woolen  or  cotton  fibres,  dung,  etc.).  These  impurities 
may  be  separated  by  repeated  dilution  of  the  milk  with 
pure  distilled  water,  leaving  the  mixture  undisturbed 
for  a  couple  of  hours  each  time  before  the  liquid  is 
syphoned  off.  When  the  milk  has  bee,n  entirely  re- 
moved in  this  manner,  the  residue  is  filtered  off,  dried 
and  weighed.  A  quart  of  milk  or  cream  should  not 
give  any  visible  sediment  on  standing  for  several  hours. 

A  simple  and  striking  method  of  showing  dirt 
in  milk  has  been  suggested  by  Gerber.  About  a  pint  of 
milk  is  poured  into  an  inverted  bottomless  long-necked 
bottle,  over  the  mouth  of  which  a  piece  of  cotton  is 
placed.  The  milk  will  filter  through,  leaving  the  dirt 
on  the  cotton,  which- 
is  then  removed  and 
can  be  shown  to  the 
producer  of  the 
milk.1  Li 

A  modification  of 
the  apparatus  used 
has  been  published 
by  Wisconsin  experi- 
ment station.2  About 
one  pint  of  milk  is 
strained  through  a 
cotton  disc  which  is 
held  in  the  lower 
opening  of  a  small 
metal  cylinder  (see 
Fig.  62).  This  disc 

is   then    removed    and  Milk  Sediment  Test  Discs. 

•Hoard's    Dairyman.    Nov.    •_>«.    1907. 
*Bu!l.   195  and   fMreular  41. 


252  Testing  Milk  and  Its  Products. 

furnishes  evidence  of  the  degree  of  cleanliness  with 
which  the  milk  has  been  handled.  A  rubber  bulb  is 
attached  to  the  top  of  the  cylinder  to  force  the  milk 
through  the  cotton 'disc. 

DETECTION  OP  PRESERVATIVES  IN  DAIRY  PRODUCTS. 

299.  a.  Boracic   acid    (borax,    borates,    preservaline, 
etc.).     100  cc.  of  milk  are  made  alkaline  with  a  soda 
or  potash  solution,  and  then  evaporated  to  dryness  and 
incinerated.     The  ash  is  dissolved  in  water  to  which  a 
little  hydrochloric  acid  has  been  added,  and  the  solu- 
tion filtered.     A  strip  of  turmeric  paper  moistened  with 
the  filtrate  will  be  colored  reddish  brown  when  dried  at 
100°  C.  on  a  watch  glass,  if  boracic  acid  is  present. 

If  a  little  alcohol  is  poured  over  the  ash  to  which  con- 
centrated sulfuric  acid  has  been  added,  and  fire  is  set 
to  the  alcohol,  this  will  burn  with  a  yellowish  green 
tint,  especially  noticeable  if  the  ash  is  stirred  with  .a 
glass  rod  and  when  the  flame  is  about  to  go  out. 

300.  The  following  modification  of  the  first  test  given  is  said 
to  show  the  presence  of  only  a  thousandth  of  a  grain  of  borax 
in  a  drop  of  milk   (about  .15  per  cent.)  :* 

Place  in  a  porcelain  dish  one  drop  of  milk  with  two  drops  of 
strong  hydrochloric  acid  and  two  drops  of  saturated  turmeric 
tincture;  dry  this  on  the  water  bath,  cool  and  add  a  drop  of 
ammonia  by  means  of  a  glass  rod.  A  slaty  blue  color  changing 
to  green  is  produced  if  borax  is  present.4 

301.  b.  Bi-carbonate    of   soda.     100  cc.   of   milk  to 
which  a  few  drops  of  alcohol  are  added,  are  evaporated 
and  carefully  incinerated;  the  proportion  of  carbonic 
acid  in  the  ash  as  compared  with  that  of  milk  of  known 
purity  is  determined.     If  an  apparatus  for  the  deter- 

*N.  J.  Dairy  Commissioner,  report,  1896    p.  36. 
«  See  also  par.  161. 


Chemical  Analysis  of  Milk  and  Its  Products.      253 

mination  of  carbonic  acid  is  available,  like  the  Scheibler 
apparatus,  etc.,  the  per  cent,  of  carbonic  acid  per  gram 
of  ash  (and  quart  of  milk)  can  be  easily  ascertained. 
Normal  milk  ash  contains  only  a  small  amount  of  car- 
bonic acid  (less  than  2  per  cent.),  presumably  formed 
from  the  citric  acid  of  the  milk  in  the  process  of  incin- 
eration. 

The  following  qualitative  test  is  easily  made:  To  10 
cc.  of  milk  add  10  cc.  of  alcohol  and  a  little  of  a  one 
per  cent,  solution  of  rosolic  acid  (corallin).  Pure  milk 
will  give  a  brownish  yellow  color ;  milk  to  which  soda  has 
been  added,  a  rose  red  color.  A  control  experiment  with 
milk  of  known  purity  should  be  made. 

302.  c.  Fluorids.     100  cc.  of  milk  are  evaporated  in 
a  platinum  or  lead  crucible,  and  incinerated;  the  ash  is 
made  strongly  acid  with  concentrated  sulfuric  acid.    If 
fluorids  are  present  hydrofluoric  acid  will  be  generated 
on  gentle  heating  and  will  be  apparent  from  its  staling 
a  watch  glass  placed  over  the  crucible.1 

303.  d.  Salicylic   acid    (salicylates,  etc.).    20  cc.  of 
milk  are  acidulated  with  sulfuric  acid  and  shaken  frith 
ether;  the  ether  solution  is  evaporated,  and  the  residue 
treated  with  alcohol  and  a  little  iron-chlorid  solution; 
a  deep  violet  color  will  be  obtained  in  the  presence  of 
salicylic  acid. 

304.  e.  Formaldehyde   (a  forty-per  cent,  solution  in 
water) . 

The  following  method  by  Hehner  is  stated  to  show 
the  presence  of  one  part  of  formaldehyde  in  200,000 


1  Chromates  In  dairy  products  may  be  readily  determined  by  the  use 
ol  a   silver-nitrate  solution,   see   Molkerei-Ztg.    (Berlin)    1899,    p.    603. 


254  Testing  Milk  and  Its  Products. 

parts  of  milk:  the  milk  is  diluted  with  an  equal  volume 
of  water,  and  strong  H2S04  (sp.  gr.  1.82-1.84)  is  added. 
A  violet  ring  is  formed  at  the  junction  of  the  two 
liquids  if  formaldehyde  is  present ;  if  not,  a  slight  green- 
ish tinge  will  be  seen.  The  violet  color  is  not  obtained 
with  milk  containing  over  .05  per  cent  formaldehyde.1 

The  same  color  reaction  is  obtained  in  the  Babcock 
test  and  is  easily  recognized  by  persons  familiar  with 
milk  testing  when  their  attention  has  once  been  called 
to  the  characteristic  color. 

An  adulteration  of  milk  with  formaldehyde  may  be 
readily  detected  by  the  following  method,  which  will 
show  the  presence  of  only  a  trace  of  formaldehyde  in 
the  milk.  5  cc.  of  milk  is  measured  into  a  white  porce- 
lain dish,  and  a  similar  quantity  of  water  added.  10 
cc.  of  HC1  containing  a  trace  of  Pe2Cl6  is  added,  and 
the  mixture  is  heated  very  slowly.  If  formaldehyde  is 
present,  a  violet  color  will  be  formed. 

1  Chem.  News,  1896,  No.  71 ;  Milchzeitung,  1896,  491 ;  1897,  40, 
667;  The  Analyst,  1895,  152,  154,  157;  1896,  285. 


GOVERNMENT  STANDARDS   OF    PURITY 
FOR  MILK  AND  ITS  PRODUCTS.1 


1.  Milk  is  the   fresh,  clean,  lacteal  secretion  obtained  by   the 
complete    milking    of    one    or    more    healthy    cows,    properly    fed 
and  kept,  excluding  that  obtained  within  fifteen  days  before  and 
ten  days  after  calving,  and  contains  not  less  than  eight  and  one 
half   (8.5)    per  cent,  of  solids  not  fat,  and   not  less  than   three 
and  one-quarter  (3.25)  per  cent,  of  milk  fat. 

2.  Blendid  milk  is  milk  modified  in  its  composition  so  as  to 
have  a  definite  and  stated  percentage  of  one  or  more  of  its  con 
stituents. 

3.  Skim  milk  is  milk  from  which  a  part  or  all  of  the  cream 
has  been  removed  and  contains  not  less  than  nine  and  one-quarter 
(9.25)   per  cent,  of  milk  solids. 

4.  Pasteurized  milk  is  milk  that  has  been  heated  below  boil- 
:ng  but  sufficiently  to  kill  most  of  the  active  organisms  present 
and  immediately  cooled  to  50°  Fehr.  or  lower. 

5.  Sterilized  milk  is  milk  that  has  been  heated  at  the  tern 
perature  of   boiling  water  or   higher   for  a  length   of   time   suffi 
cient  to  kill  all  organisms  present. 

6.  Condensed  milk,  evaporated  milk  is   milk  from   which  a 
considerable  portion  of  water  has  been  evaporated  and  contains 
not  less  than  twenty-eight  (28)  per  cent,  of  milk  solids,  of  which 
not   less   than    twenty-seven   and   five-tenths    (27.5)    per    cent,    is 
milk  fat. 

7.  Sweetened  condensed  milk,  sweetened  evaporated  milk, 
sweetened  concentrated  milk,  is  the  product  resulting  from 
the  evaporation  of  a  considerable  portion  of  the  water  from 
the   whole,   fresh,   clean,   lacteal   secretion   obtained  by  the 
complete  milking  of  one  or  more  healthy  cows,  properly  fed 
and  kept,  excluding  that  obtained  within  fifteen  days  before 
and  ten  days  after  calving,  to  which  sugar    (sucrose)    has 

1  Circular  No.  19,  Office  of  the  Secretary.  TJ.  S.  Dept.  of  Agriculture, 
June  26.  1906. 


256  Testing  Milk  and  Its  Products. 

been  added.  It  contains,  all  tolerances  being  allowed  for  not 
less  than  twenty-eight  per  cent  (28%)  of  total  milk  solids, 
and  not  less  than  eight  per  cent  (8%)  of  milk  fat. 

8.  Condensed  skimmed  milk,  evaporated   skimmed    milk, 
concentrated   skimmed  milk,   is  the  product  resulting   from 
the  evaporation  of  a  considerable  portion  of  the  water  from 
skimmed  milk,  and  contains,  all  tolerances  being  allowed  for, 
not  less  than  twenty  per  cent  (20%)  of  milk  solids. 

9.  Sweetened  condensed  skimmed  nr'k,  sweetened   evap- 
orated skimmed  milk,  sweetened  concentrated  skimmed  milk, 
is  the  product  resulting  from  the  evaporation  of  a  consider- 
able portion  of  the  water  from  skimmed  milk  to  which  sugar 
(sucrose)   has  been  added.     It  contains,  all  tolerances  being 
allowed  for,  not  less  than  twenty-eight  per  cent   (28%)    of 
milk  solids. 

10.  Dried  milk   is  the  product  resulting  from  the  removal 
of  water  from  milk,  and  contains,   all  tolerances  being  al- 
lowed for,  not  less  than  twenty-si*  per  cent  (26.0%)  of  milk 
fat,  and  not  more  than  five  per  cent  (5.0%)  of  moisture. 

11.  Dried  skimmed  milk  is  the  product  resulting  from  the 
removal  of  water  from  skimmed  milk  and  contains,  all  toler- 
ances being- allowed  for,  not  more  than  five  per  cent  (5.0%) 
of  moisture. 

12.  Malted  milk  is  the  product  made  by  combining  whole 
milk  with  the  liquid  separated  from  a  mash  of  ground  barley 
malt  and  wheat  flour,  with  or  without  the  addition  of  sodium 
chlorid,   sodium   bicarbonate,    and   potassium   bicarbonate   in 
such  a  manner  as  to  secure  the  full  enzymic  action  of  the 
malt  extract  and  by  removing  water.     The  resulting  product 
contains  not  less  than  seven  and  one-half  per  cent   (7.5%) 
of  butterfat  and  not  more  than  three  and  one-half  per  cent 
(3.5%)   of  moisture. 

13.  Buttermilk  is  the  product  that  remains  when  butter  is  re- 
moved from  milk  or  cream  in  the  process  of  churning. 

14.  Goat's  milk,  ewe's  milk,  etc.,   are  the  fresh,  clean,  lac- 
teal  secretions,    free   from   colostrum,    obtained   by    the    complete 
milking  of   healthy  animals   other   than   cows,   properly   fed  and 
kept,  and  conform  in  name  to  the  species  of  animal  from  which 
they  are  obtained. 


Government  Standards  of  Purity.  257 


b.      CREAM. 

£  1.  Cream  is  that  portion  of  milk,  rich  in  milk  fat,  which 
rises  to  the  surface  of  milk  on  standing,  or  is  separated  from  it 
by  centrifugal  force,  is  fresh  and  clean  and  contains  not  less 
than  eighteen  (18)  per  cent,  of  milk  fat. 

2.  Evaporated  cream,  clottedjcream,  is  cream  from  which 
a  considerable  portion  of  water  has  been  evaporated. 

C.      MILK  FAT  OR  BUTTER  PAT. 

1.  Milk  fat,  butter  fat,  is  the  fat  of  milk  and  has  the  Reich- 
ert-Meissl  number  not  less  than  twenty-four  (24)  and  a  specific 
gravity  of  not  less  than  0.905 


d.      BUTTER. 

T  1.  Butter  is  the  clean,  non-rancid  product  made  by  gather- 
ing in  any  manner  the  fat  of  fresh  or  ripened  milk  or  cream 
into  a  mass,  which  also  contains  a  small  portion  of  the  other 
milk  constituents,  with  or  without  salt,  and  contains  not  less 
than  eighty-two  and  five-  tenths  (82.5)  per  cent,  of  milk  fat.  By 
acts  of  Congress  approved  August  2,  1886,  and  May  9,  1902, 
butter  may  also  contain  added  coloring  matter. 

2.*{  Renovated  butter,  process  butter,  is  the  product  made 
by  melting  butter  and  reworking,  without  the  addition  or  use  of 
chemicals  or  any  substances  except  milk,  cream,  or  salt,  and 
contains  not  more  than  sixteen  (16)  per  cent,  of  water  and  at 
least  eighty-  two  and  five-tenths  (82.5)  per  cent,  of  milk  fat. 

6.      CHEESE. 

1.  Cheese  is  the  sound,  solid,  and  ripened  product  made  from 
milk  or  cream  by  coagulating  the  casein  thereof  with  rennet  or 
lactic   acid,  with  or  without  the  addition   of  ripening  ferments 
and  seasoning,  and  contains,  in  the  water-free  substance,  not  less 
than  fifty   (50)   per  cent,  of  milk  fat.     By  act  of  Congress,  ap- 
proved  June   6,   1896,    cheese   may   also    contain    added   coloring 
matter. 

2.  Skim  milk  cheese  is  the  sound,  solid,  and  ripened  product, 
made    from    skim   milk   by   coagulating   the   casein    thereof   with 

17 


258  Testing  Milk  and  Its  Products. 

rennet  or  lactic  acid,  with  or  without  the  addition  of  ripening 
ferments  and  seasoning. 

3.     Goat's  milk  cheese,  ewe's  milk   cheese,  etc.,    are   the 

sound,  ripened  products  made  from  the  milks  of  the  animals 
specified,  by  coagulating  the  casein  thereof  with  rennet  or  lactic 
acid,  with  or  without  the  addition  of  ripening  ferments  and 
seasoning. 

f.      ICE  CREAMS. 

1.  Ice  cream  is  a  frozen  product  made  from  cream  and  sugar, 
with  or  without  a  natural  flavoring,  and  contains  not  less  than 
fourteen  (14)  per  cent,  of  milk  fat. 

2.  Fruit  ice  cream  is   a   frozen   product   made   from   cream, 
sugar,  and  sound,  clean,  mature  fruits,  and  contains  not  less  than 
twelve  (12)  per  cent,  of  milk  fat. 

3.  Nut  ice  cream  is    a    frozen   product    made   from    cream, 
sugar,    and   sound,   non-rancid   nuts,   and    contains  not  less  than 
twelve  (12)  per  cent,  of  milk  fat. 

g-     MISCELLANEOUS  MILK  PRODUCTS. 

1.  Whey  is  the  product  remaining  after  the  removal  of  fat 
and  casein  from  milk  in  the  process  of  cheese-makiug. 

2.  Kumiss  is  the  product  made  by  the  alcoholic  fermentation 
of  mare's  or  cow's  milk. 


307.     SPECIFICATIONS  FOR  STANDARD 
BABCOCK  GLASS  WARE. 

(Adopted  by  the  Official  Dairy  Instructors'  Association,  1911) 


I.     Milk  Test  Bottle.     8%  18  gram,  so-called  6-inch. 

Graduation:  The  total  per  cent  graduation  shall  be  8.  The 
graduated  portion  of  the  neck  shall  have  a  length  of  not  less  than 
63.5  mm.  (2*&  inches).  The  graduation  shall  represent  whole  per 
cent,  five-tenths  per  cent  and  tenths  per  cent.  The  tenths  per  cent 
graduations  shall  not  be  less  than  3  mm.  in  length;  the  five-tenths 
per  cent  graduations  shall  be  1  mm.  longer  than  the  tenth  per  cent 
graduations,  projecting  1  mm.  to  the  left;  the  whole  per  cent 
graduations  shall  extend  one-half  way  around  the  neck  to  the  right 
and  projecting  2  mm.  to  the  left  of  the  tenths  per  cent  gradua- 
tions. Each  per  cent  graduation  shall  be  numbered,  the  number 
being  placed  on  the  left  of  the  scale.  The  error  at  any  point  of 
the  scale  shall  not  exceed  one-tenth  per  cent. 

Neck:  The  neck  shall  be  cylindrical  for  at  least  9  mm.  below 
the  lowest  and  above  the  highest  graduation  mark.  The  -top  of 
the  neck  shall  be  flared  to  a  diameter  of  not  less  than  10  mm. 

Bulb:  The  capacity  of  the  bulb  up  to  the  junction  of  the  neck 
shall  not  be  less  than  45  cc.  The  shape  of  the  bulb  may  be  either 
cylindrical  or  conical,  with  the  smallest  diameter  at  the  bottom. 
If  cylindrical,  the  outside  diameter  shall  be  between  34  and  36 
mm.;  if  conical,  the  outside  diameter  of  the  base  shall  be  between 
31  and  33  mm.,  and  the  maximum  diameter  between  35  and  37  mm. 

The  Charge  of  the  bottle  shall  be  18  grams. 

The  Total  Height  of  the  bottle  shall  be  between  150  and  165 
mm.  (5%  and  6^  inches). 

Each  bottle  shall  bear  a  permanent  identification  number. 

II. \  Cream  Test  Bottles.  50%  9-gram,  so-called  6-inch,  and 
50%  9-gram,  so-called  9-inch. 

A.  50%  D-  gram,  so-called  6-inch. 

Graduation:  The  total  per  cent  graduation  shall  be  50.  The 
graduated  portion  of  the  neck  shall  have  a  length  of  not  less 
than  63.5  mm.  (2^  inches).  The  graduation  shall  represent  5 
per  cent,  1  per  cent  and  five-tenths  per  cent.  The  five-tenths  per 
cent  graduations  shall  be  at  least  3  mm.  in  length ;  the  1  per  cent 


258b  Specifications  for  Glassware. 

graduations  shall  be  2  mm.  longer  than  the  five-tenths  per  cent 
graduations,  projecting  2  mm.  to  the  left;  the  5  per  cent  gradua- 
tions shall  extend  half  way  around  the  neck  to  the  right  and  pro- 
ject 4  mm.  to  the  left  of  the  five-tenths  per  cent  graduations. 
Each  5  per  cent  graduation  shall  be  numbered,  the  number  being 
placed  on  the  left  of  the  scale.  The  error  at  any  point  of  the 
scale  shall  not  exceed  five-tenths  per  cent. 

Neck:  (Same  as  standard  milk  test  bottle.)  The  neck  shall 
be  cylindrical  for  at  least  9  mm.  below  the  lowest  and  above  the 
highest  graduation  mark.  The  top  of  the  neck  shall  be  flared  to  a 
diameter  of  not  less  than  10  mm. 

Bulb:  (Same  as  standard  milk  test  bottle.)  The  capacity  of 
the  bulb  up  to  the  junction  of  the  neck  shall  not  be  less  than 
45  cc.  The  shape  of  the  bulb  may  be  either  cylindrical  or  conical, 
with  the  smallest  diameter  at  the  bottom.  If  cylindrical  the  out- 
side diameter  shall  be  between  34  and  36  mm.;  if  conical,  the 
outside  diameter  of  the  base  shall  be  between  31  and  33  mm.  and 
the  maximum  diameter  between  35  and  37  mm. 

The  Charge  of  the  bottle  shall  be  9  grams.  All  bottles  shall 
bear  on  top  of  the  neck  above  the  graduations  in  plainly  legible 
characters,  a  mark  defining  the  weight  of  the  charge  to  be  used 
(9  grams). 

The  Total  Height  of  the  bottJe  shall  be  between  150  and  165 
mm.  (5%  and  6%  inches).  (Same  as  standard  milk  test  bottles.) 

Each  bottle  shall  bear  a  permanent  identification  number. 

B.  50%  9-gram,  so-called  9-inch. 

The  same  specifications  in  every  detail  as  specified  for  the  50% 
9-gram  6-inch  cream  test  bottle  shall  apply  to  the  9-inch  bottle, 
with  the  exception,  however,  that  the  total  height  of  this  bottle 
shall  be  between  210  and  225  mm.  (8%  and  8%  inches). 

III.  The  Standard  Babcock  Pipette.  Total  length  of 
pipette  not  more  than  330  mm.  (13^4  inches).  Outside  diameter 
of  suction  tube  6  to  8  mm.  Length  of  suction  tube  130  mm.  Out- 
side diameter  of  delivery  tube,  4.5  to  5.i)  mm.  Length  of  deliv- 
ery tube,  100  to  120  mm.  Distance  of  graduation  mark  above  bulb, 
30  to  60  mm.  Nozzle  straight.  Delivery  17.6  cc.  of  water  at  20 
degrees  C.  in  5  to  8  seconds. 

In  view  of  the  fact  that  the  skimmilk  bottle  can  give  only  ap- 
proximate quantitative  results,  it  should  be  given  no  consideration 
as  a  standard  bottle. 


APPENDIX. 


Table  I.     Composition  of  milk  and  its  products. 


No.  of 

SMljTMt 

Want 

Fst 

Cucin 
and 
ilbamtn 

Milk 

Ask 

Authority 

Cow'  •milk... 

793 

pr.  ct. 
87.17 
87.75 
87.10 
86.48 
87.10 
74.57 
68.82 
73.90 
90.43 
90.52 
90*30 
90.12 
91.87 
93.381 
93.lt 

58.99 

25.61 
11.95 
12.93 
13.08 
13.07 
11.57 
36.33 
38.00 
36.84 
34.38 

32.06 
39.79 
46.00 
50.5 

pr.  ct. 
3.69 
3.40 
3.90 
4.20 
3.90 
3.59 
22.66 
17.60 
-    .87 
.32 
.10 
1.09 
.27 
.12 
.27 

12.42 

10.35 
84.27 
84.53 
84.26 
85.24 
84.70 
40.71 
30.25 
33.83 
32.71 

34.43 

23.92 
11.65 
1.2 

t& 

3.50 
3.201 
3.  51* 
3.40 
17.64* 
3.76 

Pf.  Ct. 

4.88 
4.60 
5.10 

'i!85 
2.67 
4.23 

pt.  ct. 
.71 
.75 
.70 
•.71 
.75 
1.56 
.53 
.62 
.70 

K6nig' 

Fleischmanu 
Van  Slyke 
Holland* 
Richmond 
K5nig§ 

Holland* 
K6nig» 
Holland* 
Van  Slyke 
K6nig» 
Holland* 
K6nig» 
Van  81yk« 

ESnig* 

44 

Well 

K5nig» 

Won 

Farrington 
Konig- 

Van  Slyk* 
Drew 

Shntt 
K6nig» 

S  torch 

.7     ^5. 

44        « 

5,552 
2,173 
200,000 
42 
43 
203 
56 
354 

14               II 

II               II 

Colostrum  milk  

Cream  

Cream,  Cooley  

Skim  milk  (gravity).. 

Skim  milk   (centrifugal) 
Butter  milk  

3.26 

4.74 

3.55 
4.03 

5.25 

4.04 

.80 
;72 

57 
31 
46 

14                « 

Whey  .. 

.86 
.81 

11.92 

11.79 
1.3 
.61 
.81 

1.5 
.8 
18.84 
25.35 
23.72 
26.38 

28.00 
29.67 
34.06 
43.1 

4.79| 
5. 

14.49 

50.06 
6 
.68 
.66 
7 
•5 
1.02 
1.43 
5. 
2.95 

5. 

1.79 

- 

.65 

to 

2.18 

.19 
.58 
.25 
.19 
.12 
.78 
.10 
.97 
51 
3.58 

>1 
4.73 
4.87 
5.2 

TTIWJ 

Condensed  milk, 
(no  sugar  added)... 
Condensed  milk, 
(sugar  added)  ...... 

36 

64 
1,676 
10 
11 
242 
350 
127 
143 

Butter   salted  

"        sweet  cream.. 
"       sour  cream... 
"       nnsalted  
"     World'.  Fair.  1893 
Cheese  cream       ... 

"       full  cream.... 
"       eheddar,  green 
"       eheddar,  cured 
"       World's  Pair 
Mam'th,  1893 
44       half-skim  .... 
"        skim. 

27 

1 
21 
41 

"        centrifugal  skim  . 

1  .70  per  cent,  albumen.                               *  18.60  per  cent,  albumen. 
*  Forty-two  analyses.                                    *  Mostly  European  samples. 
*  Right  analyses.                                             *  Massachusetts'  samples. 

260  Testing  Milk  and  Its  Products. 

Legal  Standards  for  Dairy  Products 

(Cir.  218.    Bur.  An.  Ind.  U.  S.  Dept.  of  Agric.) 


States 

Milk 

Skim 
milk 

Cream 

But- 
ter 

Whole 
milk 
cheese 

Condensed 
milk 

lee  cream 

Plain 

Fruit 
and 
nut 

Total 
solids 

Solids 
not 
fat 

Fat 

Total 
solids 

Fat 

Pr.ct. 
18.0 

Fat 

Fat 

Total 
solids 

Fat 

Fat 

Fat 
Pr.ct. 

Cal  

Pr.ct. 
11.5 

Pr.ct. 
8.5 

Pr.et. 
3.0 

Pr.ct. 

8.8 

Pr.ct. 
80.0 

Pr.ct. 
•50 

Pr.ct. 

n 

Pr.ct. 
<*) 

Pr.ct. 
12 

Colo  





3.0 



'16.0 

80.0 

150 



14 

12 

Conn.  

11.75 

8.5 

3.25 

16.0 







Dint.  Col  

12.5 

•  9.0 

3.5 

9.3 

20.0 

83.0 











Fla  

11.75 

8.5 

3.25 

9.25 

18.0 

82.5 

150 

*28.0 

«7.7 

12 



Ga  

11.75 

8.5 

3.25 

9.25 

18.0 

82.5 

150 

28.0 

1  27.  66 

14 

12 

Hawaii*  

11.5 

8.5 

3.0 









28.0 

7.7 





Idaho  

11.2 

8.0 

3.2 

9.3- 

18.0 

8.25 

30 

W 

(2) 

14 

12 

Ill  

11.5 

8.5 

3.0 

9.25 

18.0 

82.5 

150 

(*) 

(*) 

8 



Ind  



8.5 

3.25 

9.26 

18.0 

82.5 

150 

28.0 

127.5 

8 



Iowa  

12.0 

3.0 



16.0 

6  80.0 



12 



Kans  

11.75 

8.5 

3.25 

9.25 

»18.0 

80.0 

150 

(') 

(2) 

14 

12 

Ky  

12.5 

8.5 

3.25 

9.26 

18.0 

82.5 

150 

28.0 

126.76 

14 

12 

La  



8.5 

3.5 

8.0 

18.0 





•P) 

(') 

Me  

11.75 

8.5 

3.25 

18.0 







Md.  

12.5 



3.5 

9.25 

18.0 



(') 

P) 

4 

6 

Mass  

12.15 

3.25 

9.3 

15.0 



?.. 



Mich  

12.5 



3.0 





12 



Minn  

13.0 

9.75 

3.25 



20.0 



145 

(*) 

W 

12 



Mo  

12.0 

8.75 

3.25 

9.25 

18.0 

8.25 

150 

28.0 

»7.76 

14 



Mont  

11.75 

8.5 

3.25 

20.0 

8.25 

150 





14 



Neb  





3.0 



18.0 









14 

12 

'  Percentage  of  fat  based  on  total  solids. 
«  Fat,  7.8  per  cent;  total  solids  plus  fat,  34.3  per  cent 
•  For  buttermaking,  25  per  cent  fat. 

4  Thii  standard  for  sweetened  condensed  milk:  "Evaporated  milk,"  solids,  24  per  cent;  fat, 
7.8  per  cent. 
•So  report;  1910  rtandard  given. 


Appendix. 

LEGAL  STANDARDS  FOR  DAIRY  PRODUCTS— Continued 


261 


States 

Milk 

Skim 
milk 

Cream 

But- 
ter 

a- 

cheese 

Condensed 

Ice  cream 

Plain 

Fruit 
and 
nut 

Total 
solids 

Solids 
not 
fat 

Fat 

Total 
solids 

Fat" 

Fat 

Fat 

Total 
solids 

Fat 

Fat 

Fat 

N.  H  

Pr.et. 
12.0 

Pr.ct. 

Pr.ct. 

Pr.et. 
8.5 

Pr.ct. 
18.0 

Pr.et. 
80.0 

Pr.ct. 

Pr.ct. 

Pr.d. 

Pr.d. 
»14 

Pr.d. 

N.  J  

11.5 



3.0 

16.0 









N.  Y  

11.5 



3.0 

18.0 



(') 

'25.0 



Nev  

11.75 

8.5 

-3.25 

9.25 

18.0 

82.5 

>50 

26.5 

7.8 

14 



N.  C  

11.75 

8.5 

3.25 

9.25 

18.0 

82.5 

»50 

28.0 

»27.5 

14 

12 

N.  Dak  

12.0 

9.0 

3.0 



15.0 









14 



Ohio  

12.0 



3.0 



80.0 

(•) 

»25.0 



Okla  

12.51 

0.5 

3.0 



18.0 

81.5 







14 



Ore  



9.0 

3.2 



20.0 

30.0 

0 

(7) 

12 



Pa....:  

12.0 



3.25 



18.0 



32.0 





8 

6 

Porto  Rico.. 

12.0 

9.0 

3.0 











R.  I  

12.0 



2.5 













S.  Dak  



8.5 

3.25 

9.25 

18.0 

80.0 

>50 

28.0 

27.5 

14 

12 

Tenn  



8.5 

3.25 



Texas  

8.5 

3.25 



Utah  

12.0 

9.0 

3.2 

9.0 

18.0 

80.0 

>50 

(') 

(*) 

14 

12 

Vt  

12.5 

9.25 















Va  

11.75 

8.5 

3.25 

9.25 

18.0 

82.5 

(') 

P) 

8 



Wash  

12.0 

8.75 

3.25 

9.3 

18.0 



30 







Wis  



8.5 

3.0 

9.0 

18.0 

82.5 

>50 

28.0 

8.0 

14 



Wyo  



8.5 

3.25 

9.25 

18.0 

82.5 

'50 

28.0 

(•) 

14 

12 

1  Percentage  of  fat  based  on  total  solids. 
J  Fat,  7.8  per  cent;  total  solids  plus  fat,  34.3  per  cent. 
1  Not  more  than  0.2  per  cent  "filter." 
4  Must  correspond  to  11.5  per  cent  solids  in  crude  milk. 
« If  artificially  colored. 

8  Must  correspond  to  12  per  cent  solid  in  crude  milk. 

7  23-24  per  cent  solids,  7.9  per  cent  fat;  24-25  per  cent  solids,  7.8  per  cent  fat;  25-26  per  cent 
solids,  7.7  per  cent  fat;  26  per  cent  solids,  7.6  per  cent  fat. 
>  In  May  and  June,  solids  12  per  cent. 
•  Fat.  27.5  per  cent  of  total  solids. 


262 


Testing  Milk  and  Its  Products. 


lactometer  degrees  corresponding  to 
N.  Y.  Board  of  Health  degrees.     (See  par.  114) 


Bd.  o<  Health 
degrees. 

*sr 

Bd.  of  Health 

Qutvennc 
scale. 

Bd.  of  Health 
degrees. 

Quevenne 

scale. 

60 

17.4 

81 

23.5 

101 

29.3 

61 

17.7 

82 

23.8 

102 

29.6 

« 

18.0 

83 

24.1 

103 

29.9 

63 

18.3 

84 

24.4 

104 

80.2 

64 

1S.6 

85 

24.6 

105 

80.5 

65 

18.8 

86 

24.9 

106 

80.7 

66 

i».i 

87 

25.2 

107 

8LO 

67 

19.4 

88 

25.5 

108 

81.8 

68 

19.7 

89 

25.8 

109 

31.6 

69 

20.0 

90 

26.1 

110 

31.9 

70 

20.3 

91 

26.4 

111 

82.2 

71 

20.6 

92 

26.7 

112 

82.6 

72 

20.9 

93 

27.0 

118 

32.8 

73 

21.2 

94 

27.3 

114 

88.1 

74 

21.5 

95 

27.6 

116 

83.4 

75 

21.7 

96 

27.8 

118 

83.6 

76 

22.0 

97 

28.1 

117 

83.9 

77 

22.8 

98 

28.4 

118 

84.1 

78 

22.6 

99 

28.7 

119 

84.6 

79 

22.9 

100 

29.0 

120 

84.8 

80 

23.2 

Table  IV.    Value  of 


for  sp.  gr.  from  1.019  to  1.0369. 


.*r.(g)= 

0.0000 

0.0001 

0.0002 

0.0003 

0.0004 

0.0005 

0.0006 

0.0007 

0.0008 

0.0009 

1.019 

1.864 

1.874 

1.884 

1.894 

1.903 

1.913 

L922 

L932 

1.941 

1.951 

.020 

1.961 

L970 

1.980 

1.990 

1.999 

2.009 

2.018 

2.028 

2.038 

2.047 

.021 

2.057 

2.066 

2.076 

2.086 

2.095 

2.105 

2.114 

2.124 

2.183 

2.143 

.022 

2.153 

2.162 

2.172 

2.181 

2.191 

2.200 

2.210 

2.220 

2.229 

2.239 

.028 

2.249 

2.258 

2.267 

2.277 

2.286 

2.296 

2.306 

2.815 

2.825 

2.334 

.024 

2.344 

2.353 

2.363 

2.372 

2.382 

2.391 

2.401 

2.410 

2.420 

2.430 

.025 

2.439 

2.449 

2.458 

2.468 

2.477 

2.487 

2.496 

2.506 

2.515 

2.525 

.026 

2.534 

2.544 

2.553 

2.563 

2.573 

2.582 

2.591 

2.601 

2.610 

2.620 

.027 

2.629 

2.638 

2.648 

2.657 

2.667 

2.676 

2.686 

2.695 

2.705 

2.714 

.028 

2.724 

2.733 

2.743 

2.752 

2.762 

2.771 

2.781 

2.790 

2.799 

2.809 

.029 

2.818 

2.828 

2.837 

2.847 

2.856 

2.865 

2.875 

2.884 

2.893 

2.903 

.030 

2.913 

2.922 

2.931 

2.941 

2.951 

2,960 

2.969 

2.979 

2.988 

2.997 

.031 

3.007 

3.016 

3.026 

3.035 

3.044 

3.054 

3.063 

3.072 

3.082 

3.091 

.032 

3.101 

3.110 

3.120 

8.129 

3.138 

3.148 

3.157 

3.166 

3.176 

3.185 

.033 

3.195 

3.204 

3.213 

3,223 

3.232 

3.241 

3.251 

8.260 

3.269 

3.279 

.034 

3.288 

3.298 

3.307 

3.816 

3.326 

3.335 

3.344 

3.354 

3.363 

3.372 

.035 

3.382 

8.891 

3.400 

3.410 

3.419 

3.428 

8.438 

3.447 

3.456 

3.466 

.036 

3.475 

3.484 

3.494 

3.503 

8.512 

3.521 

3.531 

3.540 

3.549 

3.559 

(See  direction*  for  UM, 


Appendix.  263 

Table  V.    Correction-table  for  specific  gravity  of  milk. 


f* 

Temperature  of  milk  (In  degrees  Fahrenheit). 

J! 

51 

62 

63 

64 

66 

56 

67 

68 

69 

60 

20 

19.3 

19.4 

19.4 

19.5 

19.6 

19.7 

19.8 

19.9 

19.9 

20.0 

21 

20.3 

20.3 

20.4 

20.5 

20.6 

20.7 

20.8 

20.9 

20.9 

21.0 

22 

21.3 

21.3 

21.4 

21.5 

21.6 

21.7 

21.8 

21.9 

21.9 

22.0 

23 

22.3 

22.3 

22.4 

22.5 

22.6 

22.7 

22.8 

22.8 

22.9 

23.0 

24 

23.3 

23.3 

23.4 

23.5 

23.6 

23.6 

23  7 

23.8 

23.9 

24.0 

25 

24.2 

24.3 

24.4 

24.5 

24.6 

24.6 

24> 

24.8 

24.9 

25.0 

26 

25.2 

25.2 

25.3 

25.4 

25.5 

25.6 

25.7 

25.8 

25.9 

26.0 

27 

26.2 

26.2 

26.3 

26.4 

26.5 

26.6 

26.7 

26.8 

26.9 

27.0 

28 

27.1 

27.2 

27.3 

27.4 

27.5 

27.6 

27.7 

27.8 

27.9 

28.0 

2!) 

28.1 

28.2 

28.3 

28.4 

28.5 

28.6 

28.7 

28.8 

28.9 

29.0 

30 

29.1 

29.1 

29.2 

29.3 

29.4 

29.6 

29.7 

29.8 

29.9 

30.0 

31 

30.0 

30.1 

30.2 

30.3 

30.4 

30.5 

30.6 

30.8 

30.9 

31.0 

32 

31.0 

31.1 

31.2 

31.3 

31.4 

31.5 

31.6 

31.7 

31.9 

32.0 

33 

31.9 

32.0 

32.1 

32.3 

32.4 

32.5 

32.6 

32.7 

32.9 

33.0 

34 

32.9 

33.0 

33.1 

33.2 

33.3 

33.5 

33.6 

33.7 

33.9 

34.0 

35 

33.8 

33.9 

34.0 

34.2 

34.3 

34.5 

34.6 

34.7 

34.9 

35.0 

61 

62 

63 

64 

66 

66 

67 

68 

69 

70 

20 

20. 

20.2 

20.2 

20.3 

20.4 

20.5 

20.6 

20.7 

20.9 

21.0 

21 

21. 

21.2 

21.3 

21.4 

21.5 

21.6 

21.7 

21.8 

22.0 

22. 

22 

22. 

22.2 

22.3 

22.4 

22.6 

22.6 

22.7 

22.8 

23.0 

23. 

23 

23. 

23.2 

23.3 

23.4 

23.5 

23.6 

23.7 

23.8 

24.0 

24. 

24 

24. 

24.2 

24.3 

24.4 

24.5 

24.6 

24.7 

24.9 

25.0 

25. 

25 

25. 

25.2 

25.3 

25.4 

25.5 

25.6 

25.7 

25.9 

26.0 

26. 

26. 

26.2 

26.3 

26.5 

26.6 

26.7 

26.8 

27.0 

27.1 

27.2 

27 

27. 

27.3 

27.4 

27.5 

27.6 

27.7 

27.8 

28.0 

28.1 

28.2 

28 

28. 

28.3 

28.4 

28.5 

28.6 

28.7 

28.8 

29.0 

29.1 

29.2 

29 

29. 

29.3 

29.4 

29.5 

29.6 

29.7 

29.9 

30.1 

30.2 

30.3 

30 

30. 

30.3 

30.4 

30.5 

30.7 

30.8 

30.9 

81.1 

31.2 

31.3 

31 

31.2 

31.3 

31.4 

31.5 

31.7 

31.8 

31.9 

32.1 

32.2 

32.4 

32 

32.2 

32.3 

32.5 

32.6 

32.7 

32.9 

33.0 

33.  £ 

33.3 

33.4 

33 

33.2 

33.3 

33.5 

33.6 

33.8 

33.9 

34.0 

34.2 

34.3 

34.5 

34 

34.2 

34.3 

34.5 

34.6 

34.8 

34.9 

35.0 

35.2 

35.3 

35.5 

35 

35.2 

35.3 

35.5 

35.6 

35.8 

85.9 

36.1 

36.2 

36.4 

36.6 

DIRECTIONS.—  Bring  the  temperature  of  the  milk  to  within  10°  of 
80°  F.  Take  the  reading  of  the  lactometer  and  that  of  the  temperature  of 
the  milk;  find  the  former  in  the  first  vertical  column  of  the  table  and  the 
latter  In  the  first  horizontal  row  of  figures;  the  figure  where  the  horizontal 
and  vertical  columns  meet  Is  the  corrected  lactometer  reading;  e.g.,  ob- 
•erved,  31.0  at  67°  F. ;  corrected  reading,  81.9 


264 


Testing  Milk  and  Its  Products. 


Table  VI.  Per  cent,  of  solids  not  fat,  corresponding  to  0  to 
6  per  cent,  of  fat,  and  lactometer  readings  of  26  to 

36.     (See  directions  for  use,  par.  120) 


s 

LACTOMETER  READINGS  AT  60°  P. 

3 

«J 

•I 

JL 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

y 

0 

6.50 

6.75 

7'.  oo 

7.25 

7.50 

7.75 

8.00 

8.25 

8.50 

8.75 

9.00 

0 

0.1 

6.52 

6.77 

7.02 

7.27 

7.52 

l.TJ 

8.02 

8.27 

8.52 

8.77 

9.02 

0.1 

0.2 

6.54 

6.79 

7.04 

7.29 

7.54 

7.79 

8.04 

8.29 

8.54 

8.79 

9.04 

0.2 

0.3 

6.56 

6.81 

7.06 

7.31 

7.56 

7.81 

8.06 

8.31 

8.56 

8.81 

9.06 

0.3 

0.4 

6.68 

6.83 

7.08 

7.33 

7.58 

7.83 

8.08 

8.33 

8.58 

8.83 

9.08 

0.4 

0.5 

6.60 

6.85 

7.10 

7.35 

7.60 

7.85 

8.10 

8.35 

8.60 

8.85 

9.10 

0.5 

0  6 

6  6'? 

6  87 

7  191 

7  37 

7  69, 

7  87 

8  V> 

8  37 

8  6? 

8  87 

9  12 

0.6 

0.7 

6.64 

6.89 

7.14 

7.39 

7.64 

7.89 

8.14 

8.39 

8.64 

8.89 

9.14 

0.7 

0  8 

6  66 

6  91 

7  16 

7  41 

7  66 

7  91 

8  16 

8  41 

8  66 

8  91 

9  16 

0  8 

0.9 

6.68 

6.93 

7.18 

7.43 

7.68 

7.93 

8.18 

8.43 

8.68 

8.93 

9.18 

0.9 

i 

.0 

6.70 

6.95 

7.20 

7.45 

7.70 

7.95 

8.20 

8.45 

8.70 

8.95 

9.20 

1.0 

1 

6  79, 

6  97 

7  9,9, 

7  47 

7  7? 

7  97 

8  W 

8  47 

8  7?, 

8  97 

9  22 

1.1 

2 

6  74 

6  99 

7  94 

7  49 

7  74 

7  99 

8  94 

8  49 

8  74 

8  99 

9  94 

1  2 

.3 

6.76 

7.01 

7.26 

7.51 

7.76 

8.01 

8.26 

8.51 

8.76 

9.01 

9.26 

1.3 

.4 

6.78 

7.03 

7.28 

7.53 

7.78 

8.03 

8.28 

8.53 

8.78 

9.03 

9.28 

1.4 

.5 

6.80 

7.05 

7.30 

7.55 

7.80 

8.05 

8.30 

8.55 

8.80 

9.05 

9.30 

1.5 

.6 

6.82 

7.07 

7.32 

7.57 

7.82 

8.07 

8.32 

8.67 

8.82 

9.07 

9.32 

l.C 

.7 

6.84 

7.09 

7.34 

7.59 

7.84 

8.09 

8.34 

8.59 

8.84 

9.09 

9.34 

1.7 

.8 

6  86 

7  11 

7  36 

7  61 

7  86 

8  11 

8  36 

8  61 

R  86 

9  11 

9  37 

1  8 

.9 

6.88 

7.13 

7.38 

7.63 

7.88 

8.13 

8.38 

8.63 

8.88 

9.13 

9.39 

1.9 

2.0 

6.90 

7.15 

7.40 

7.65 

7.90 

8.15 

8.40 

8.66 

8.91 

9.16 

9.41 

2.0 

2.1 

6.92 

7.17 

7.42 

7.67 

7.92 

8.17 

8.42 

8.68 

8.93 

9.18 

9.43 

2.1 

2.2 

6.94 

7.19 

7.44 

7.69 

7.94 

8.19 

8.44 

8.70 

8.95 

9.20 

9.45 

2;2 

2.3 

6.96 

7.21 

7.46 

7.71 

7.96 

8.21 

8.46 

8.72 

8.97 

9.22 

9.47 

2.3 

2.4 

6.98 

7.23 

7.48 

7.73 

7.98 

8.23 

8.48 

8.74 

8.99 

9.24 

9.49 

2.4 

2.5 

7.00 

7.25 

7.50 

7.75 

8.00 

8.  25 

8.50 

8.76 

9.01 

9.26 

9.51 

2.5 

2.6 

7.02 

7.27 

7.52 

7.77 

8.02 

8.27 

8.52 

8.78 

9.03 

9.28 

9.53 

2.6 

2.7 

7.04 

7.29 

7.54 

7.79 

8.04 

8.29 

8.54 

8.80 

9.05 

9.30 

9.55 

2.7 

2.8 

7.06 

7.31 

7.56 

7.81 

8.06 

8.31 

8.57 

8.82 

9.07 

9.32 

9.57 

2.8 

2.9 

7.08 

7.33 

7.58 

7.83 

8.08 

8.33 

8.59 

8.84 

9.09 

9.34 

9.-V) 

2.9 

Appendix. 
Table  VI.    Per  cent,  of  solids  not  fat  (Continued"). 


LACTOMETER  READINGS  AT  60°  F. 

11 

is 

£* 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

86 

X* 

3.0 

7.10 

7.35 

7.60 

7.85 

8.10 

8.36 

8.61 

8.86 

9.11 

9.36 

9.61 

3.0 

3  1 

7  1? 

7  37 

7  6? 

7  87 

8  13 

8  38 

8  63 

8  88 

9  13 

9  38 

9  64 

3.1 

3.2 

7.14 

7.39 

7.64 

7.89 

8.15 

8.40 

8.65 

8.90 

9.15 

9.41 

9.66 

3.2 

3.3 

7.16 

7.41 

7.66 

7.92 

8.17 

8.42 

8.67 

8.92 

9.18 

9.43 

9.68 

3.3 

3.4 

7.18 

7.43 

7.69 

7.94 

8.19 

8.44 

8.69 

8.94 

9.20 

9.45 

9.70 

3.4 

3.5 

7.20 

7.45 

7.71 

7.96 

8.21 

8.46 

8.71 

8.96 

9.22 

9.47 

9.72 

3.5 

3.6 

7.22 

7.48 

7.73 

7.98 

8.23 

8.48 

8.73 

8.98 

9.24 

9.49 

9.74 

3.6 

3.7 

7.24 

7.50 

7.75 

8.00 

8.25 

8.50 

8.75 

9.00 

9.26 

9.51 

9.76 

3.7 

3.8 

7.26 

7.52 

7.77 

8.02 

8.27 

8.52 

8.77 

9.02 

9.28 

9.53 

9.78 

3.8 

3.9 

7.28 

7.54 

7.79 

8.04 

8.29 

8.54 

8.79 

9.04 

9.30 

9.55 

9.80 

3.9 

4.0 

7.30 

7.56 

7.81 

8.06 

8.31 

8.56 

8.81 

9.06 

9.32 

9.57 

9.83 

4.0 

4.1 

7.32 

7.58 

7.83 

8.08 

8.33 

8.58 

8.83 

9.08 

9.34 

9.59 

9.85 

4.1 

4.2 

7.34 

7.60 

7.85 

8.10 

8.35 

8.60 

8.85 

9.11 

9.36 

9.62 

9.87 

4.2 

4.3 

7.36 

7.62 

7.87 

8.12 

8.37 

8.62 

8.88 

9.13 

9.38 

9.64 

9.89 

4.3 

4.4 

7.38 

7.64 

7.89 

8.14 

8.39 

8.64 

8.90 

9.15 

9.40 

9.66 

9.91 

4.4 

4.5 

7.40 

7.66 

7.91 

8.16 

8.41 

8.66 

8.92 

9.17 

9.42 

9.68 

9.93 

4.5 

4.6 

7.43 

7.68 

7.93 

8.18 

8.43 

8.68 

8.94 

9.19 

9.44 

9.70 

9.95 

4.6 

4.7 

7.45 

7.70 

7.95 

8.20 

8.45 

8.70 

8.96 

9.21 

9.46 

9.72 

9.97 

4.7 

4.8 

7.47 

7.72 

7.97 

8.22 

8.47 

8.72 

8.98 

9.23 

9.48 

9.74 

9.99 

4.8 

4.9 

7.49 

7.74 

7.99 

8.24 

8.49 

8.74 

9.00 

9.25 

9.50 

9.76 

10.01 

4.9 

5.0 

.51 

7  76 

8.01 

8  ?fi 

8  51 

8  76 

9  0?, 

9  ft? 

9  52 

9.78 

10.03 

5.0 

6.1 

.53 

7.78 

8.03 

8.28 

8.53 

8.79 

9.04 

9.29 

9.54 

9.80 

10.05 

5.1 

5.2 

.55 

7.80 

8.05 

8.30 

8.55 

8.81 

9.06 

9.31 

9.56 

9.82 

10.07 

5.2 

5.3 

.57 

7.82 

8.07 

8.32 

8.57 

8.83 

9.08 

9.33 

9.58 

9.84 

10.09 

5.3 

5.4 

.59 

7.84 

8.09 

8.34 

8.60 

8.85 

9.10 

9.36 

9.61 

9.86 

10.11 

5.4 

5.5 

7.61 

7.86 

a.  11 

8.36 

8.62 

8.87 

9.12 

9.38 

9.63 

9.88 

10.13 

5.5 

5.6 

7.63 

7.88 

8.13 

8.39 

8.64 

8.89 

9.15 

9.40 

9.65 

9.90 

10.15 

6.6 

5.7 

7.65 

7.90 

8.15 

8.41 

8.66 

8.91 

9.17 

9.42 

9.67 

9.92 

10.17 

5.7 

5.8 

7.67 

7.92 

8-.  17 

8.43 

8.68 

8.94 

9.19 

9.44 

9.69 

9.94 

0.19 

5.8 

5.9 

7.69 

7.94 

8.20 

8.45 

8.70 

8.96 

9.21 

9.46 

9.71 

9.96 

10.22 

5.9 

6.0 

7.71 

7.96 

8.22 

8.47 

8.72 

8.98 

9.23 

9.48 

9.73 

9.98 

10.24 

6.0 

266  Testing  Milk  and  Its  Products. 

Directions  for  Use  of  Tables  VII,  VIII,  IX,  and  XI. 
TABLES  VII,  and  VIII.  Find  the  test  of  the  milk  in  table  VII  at 
of  cream  in  table  VIII;  the  first  or  last  horizontal  row  ol  fig- 
ures, the  amounts  of  fat  in  ten  thousand,  thousands,  hundreds, 
tens,  and  units  of  pounds  of  milk  are  then  given  in  this  verti- 
cal column.  By  adding  the  corresponding  figures  for  any  given 
quantity  of  milk  or  of  cream,  the  total  quantity  of  butter  fat 
contained  therein  Is  obtained. 

Example:    How  many  pounds  of  fat  Is  contained  In  8925  IDS.  of  milk 
testing  3.85  per  cent.?    On  p  264.  -econd  column  the  test  3.63  ii  found,  and 
by  going  downward  in  this  coiiunu  we  have: 

8000  IDS  .....  ..  ....................  292.    Ibs. 

900  Ibs  ........    82.9  Ibs. 

20  Ibs!  ......  .'.  ..............  ....       .7  Ibs, 

5  Ibg  ............................  2  Ibs. 

8925  Ibs.  of  milk.  825.8  Ibs.  of  fat 

8925  Ibs.  of  milk  testing  3.65  per  cent.,  therefore,  contains  325.S  Ibs.  of 
batter  fat. 

TABLL  IX.  The  price  per  pound  is  given  in  the  outside  vertical 
columns,  and  the  weight  of  butter  fat  in  the  upper  and  lower 
horizontal  row  of  figures.  The  corresponding  tens  of  pounds 
are  found  by  moving  the  decimal  point  one  place  to  the  left, 
the  units,  by  moving  it  two,  and  the  tenths  of  a  pound,  by 
moving  it  three  places  to  the  left  The  use  of  the  table  is, 
otherwise,  as  explained  above. 

Example:    How  much  money  Is  due  for  825.8  Ibs.  of  batter  fat  at  15% 
cents  per  pound  T    In  the  horizontal  row  of  figures  beginning  with  16^  on 
p.  247,  we  find  : 

100      Ibs  ____  .....  -------  $46.50 

20     Ibs  .....................  „-»     8.10 


825.  8  Ibs.  S50.49 

825.8  Ibs.  of  butter  fat  at  15>£  cents  per  pound,  therefore,  Is  worth  850.4*. 

TABLE  XI.  Find  the  test  of  milk  in  the  upper  or  lower  hori- 
zontal row  of  figures.  The  amounts  of  butter  likely  to  be  made 
from  ten  thousand,  thousands,  hundreds,  tens,  and  units  of 
pounds  of  milk  are  then  given  in  this  vertical  column.  The  use 
of  the  table  is,  otherwise,  as  explained  above  in  case  of  table  VII. 

Example:    How  much  butter  wi  11  5845  Ibs.  of  milk  testing  8.  8  per  cent. 
be  apt  to  make  under  good  creamery  conditions  ?    In  the  column  headed 
3.8,  we  find  : 

6000  Ibs  ...........................  209.0  Ibs. 

800  Ibs  ...........................    33;4  Ibs. 

40  Ibs  ...........................     1.7  Ibs. 

6  Ibs  .........................  ..       .2  Ibs. 

8845  Ibs.  244.8  Ibs. 

5848  Ibs.  of  milk  tost  ng  3.8  per  cent,  of  fat  will  make  about  244.8  Ibs.  of 
•utter,  under  oondltioua  similar  to  those  explained  in  par.  220. 


Appendix. 


267 


Table  VII.     Pounds  of  fat  in  I  to  10,000  Ibs.  of  milk,  testing  3.0 
to  5.35  per  cent.     (See  directions  for  use,  p.  266  ) 


1 

3.00 

3.05 

3.10 

3.15 

3;20 

3.25 

3.30 

3.35 

3.4013.45 

3.50 

3.55 

J_ 

Milk 

Milk 

Ibs. 

Ibs. 

10,000 

300 

305 

310 

315 

320 

325 

330 

335 

340 

345 

350 

355 

10,000 

9,000 

270 

275 

279 

284 

289 

293 

297 

302 

306 

311 

315 

320 

9,000 

8,000 

240 

244 

248 

252 

256 

2GO 

264 

268 

272 

276 

280 

284 

8,000 

7,000 

210 

214 

217 

221 

224 

228 

231 

235 

238 

242 

245 

249 

7,000 

6,000 

180 

183 

186 

189 

192 

U)5 

198 

201 

204 

207 

210 

213 

6,000 

5.000 

150 

153 

155 

158 

160 

163 

165 

168 

170 

173 

175 

178 

5.000 

4.000 

120 

122 

124 

126 

128 

130 

132 

134 

136 

138 

140 

142 

4.000 

3,000 

90.0 

91.5 

93.0 

94.5 

96.0 

97.5 

99.0 

101 

102 

104 

105 

107 

3,000 

2,000 

60.0 

61.0 

62.0 

63.0 

64.0 

65.0 

66.0 

67.0 

68.0 

69.0 

70.0 

71.0 

2,000 

1,000 

30.0 

30.5 

31.0 

31.5 

32.0 

32.5 

33.0 

33.5 

34.0 

34.5 

35.0 

35.5 

1,000 

900 

27.0 

27.5 

27.9 

28.4 

28.8 

29.3 

29.7 

30.2 

30.6 

31.1 

31.5 

32.0 

900 

800 

24.0 

24.4 

24.8 

25.2 

25.7 

26.0 

26.4 

26.8 

27.2 

27.6 

28.0 

28.4 

800 

700 

21.0 

21.4 

21.7 

22.1 

22.4 

22.8 

23.1 

23.5 

23.8 

§4.2 

24.5 

24.9 

700 

600 

18.0 

18.3 

18.6 

18.9 

19.2 

19.5 

19.8 

20.1 

20.4 

20.7 

21.0 

21.3 

600 

500 

15.0 

15.3 

15.5 

15.8 

10.  0 

16.3 

16.5 

16.8 

17.0 

17.3 

17.5 

17.8 

500 

400 

12.0 

12.2 

12.4 

12.6 

12.8 

13.0 

13.2 

13.4 

13.6 

13.8 

14.0 

14.2 

400 

300 

9.0 

9.2 

9.3 

9.5 

9.6 

9.8 

9.9 

10.1 

10.2 

10.4 

10.5 

10.7 

.30(1 

200 

6.0 

6.1 

6.2 

6.3 

6.4 

6.5 

6.6 

6.7 

6.8 

6.9 

7.0 

7.1 

200 

100 

3.0 

3.1 

3.1 

3.2 

3.2 

3.3 

3.3 

3.4 

3.4 

3.5 

3.5 

3.6 

100 

90 

2.7 

2.8 

2.8 

2.8 

2.9 

2.9 

3.0 

3.0 

3.1 

3.1 

3.2 

3.2 

90 

80 

2.4 

2.4 

2.5 

2.5 

2.6 

2.6 

2.6 

2.7 

2.7 

2.8 

2.8 

2.8 

80 

70 

2J 

2.1 

2.2 

2.2 

2.2 

2.3 

2.3 

2.3 

2.4 

2.4 

2.5 

2  5 

70 

60 

1.8 

1.8 

1.9 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

2.1 

.   60 

50 

1.5 

1.5 

1.6 

1.6 

1.6 

1.6 

1.7 

1.7 

1.7 

1.7 

1.8 

1.8 

50 

40 

1  ? 

1  9, 

1  ? 

1  3 

1  3 

1  3 

1  3 

1  3 

1  4 

1  4 

1  4 

1  4 

40 

80 

.9 

.9 

.9 

.9 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

30 

20 

6 

6 

i* 

ft 

6 

7 

7 

7 

7 

7 

7 

7 

20 

10 

.3 

.3 

.3 

.3 

.8 

'.3 

.3 

.3 

.3 

.3 

.4 

.4 

10 

9 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.8 

.8 

.3 

.3 

.3 

9 

8 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

8 

7 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

7 

g 

2 

2 

.2 

2 

2 

2 

? 

ft 

2 

Q 

2 

6 

5 

'.2 

'.2 

.2 

.'2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

.1 

.1 

.'l 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

4 

3 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

3 

2 

.1 

.1 

.1 

.1 

.1 

1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

I 

3.00 

J 

3.05 

3.10 

3.15 

3.20 

3.25 

3.30 

3.35 

3.40 

3.45 

1.50 

!  .  5f> 

268 


Testing  Milk  and  Its  Products. 


Table  VII.    Pounds  of  fat  in  I  to  10,000  Ibs.  of  milk  (Continued). 


1 

3.60 

3.65 

3.70 

3.75 

3.80 

3.85 

3.90 

3.95 

4.00 

4.05 

4.10 

4.15 

I 

Milk 

Milk 

Ibs. 

Ibs. 

'0,000 

360 

365 

370 

375 

380 

385 

390 

395 

400 

405 

410 

415 

10,000 

9,000 

324 

329 

333 

338 

342 

347 

351 

356 

360 

365 

369 

374 

9,000 

8,000 

288 

292 

296 

300 

304 

308 

312 

316 

320 

324 

328 

332 

8,000 

7.000 

252 

256 

259 

263 

266 

270 

273 

277 

280 

284 

287 

291 

7,000 

6,000 

216 

219 

222 

225 

228 

231 

234 

237 

240 

243 

246 

249 

6,000 

5,000 

180 

183 

185 

188 

190 

193 

195 

198 

200 

203 

205 

208 

5,000 

4,000 

144 

146 

148 

150 

1  ~ir 

154 

156 

158 

160 

162 

164 

166 

4,000 

3,000 

108 

110 

111 

113 

114 

116 

117 

119 

120 

122 

123 

125 

3,000 

2,000 

72.0 

73.0 

74.0 

75.0 

76.0 

77.0 

78.0 

79.0 

80.0 

81.0 

82.0 

83.0 

2,000 

1,000 

36.0 

36.5 

37.0 

37.5 

38.0 

38.5 

39.0 

39.5 

40.0 

40.5 

41.0 

41.5 

1,000- 

900 

32.4 

32.9 

33.3 

33.8 

34.2 

34.7 

35.1 

35.6 

36.0 

36.5 

36.9 

37.4 

900 

800 

28.8 

29.2 

29.6 

30.0 

30.4 

30.8 

31.2 

31.6 

32.0 

32.4 

32.8 

33.2 

800 

700 

25.2 

25.6 

25.9 

26.3 

26.6 

27.0 

27.3 

27.7 

28.0 

28.4 

28.7 

29.1 

700 

600 

21.6 

21.9 

22.2 

22.5 

22.8 

23.1 

23.4 

23.7 

24.0 

24.3 

24.6 

24.9 

600 

500 

18.0 

18.3 

18.5 

18.8 

19.0 

19.3 

19.5 

19.8 

20.0 

20.3 

20.5 

20.8 

500 

400 

14.4 

14.6 

14.8 

15.0 

15.2 

15.4 

15.6 

15.8 

16.0 

16.2 

16.4 

16.6 

400 

300 

10.8 

11.0 

11.1 

11.3 

11.4 

11.6 

11.7 

11.9 

12.0 

12.2 

12  y 

12.5 

300 

200 

7.2 

7  3 

7  4 

7  5 

7.6 

7.7 

7.8 

7  9 

8  0 

8  1 

8  ? 

8  3 

200 

100 

3.6 

3.7 

3.7 

3.8 

3.8 

3.9 

3.9 

4.0 

4.0 

4.1 

4.1 

4.2 

100 

90 

3.2 

3.3 

3.3 

3.4 

3.4 

3.5 

3.5 

3.6 

3.6 

3.7 

3.7 

3.7 

90 

80 

2.9 

2.9 

3.0 

3.0 

3.0 

3.1 

3.1 

3.2 

3.2 

3.2 

3.3 

3.3 

80 

70 

2.5 

2.6 

2.6 

2.6 

2.7 

2.7 

2.7 

2.8 

2.8 

2.8 

2.9 

2.9 

70 

60 

2.2 

2.2 

2.2 

2.3 

2.3 

2.3 

2.3 

2.4 

2.4 

2.4 

2.5 

2.5 

60 

50 

1.8 

1.8 

1.0 

1.9 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

50 

40 

1  4 

1  fi 

1  5 

1  "> 

1  5 

1  5 

1  6 

1  6 

1  6 

1  6 

1  6 

1  7 

40 

30 

1.1 

1.1 

1.1 

1.1 

1.1 

1.2 

1.2 

1.2 

1  2 

1.2 

1.2 

1.2 

30 

20 

.7 

.7 

.7 

.8 

.8 

.8 

.8 

.8 

.8 

.8 

.8 

.8 

20 

10 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

10 

9 

ft 

ft 

ft 

ft 

ft 

3 

4 

4 

4 

4 

4 

4 

9 

8 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.8 

.3 

8 

7 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.8 

.8 

.3 

.3 

7 

3 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

6 

5 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

.1 

.1 

.1 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

8 

2 

.1 

.1 

.1 

!i 

!i 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

1 

1 

3.60 

i 

3.65 

3.70 

3.75 

3.80 

3.85 

3.90 

3.95 

4.00 

4.05 

4.10 

4.15 

i 

Appendix. 


269 


Table  VII.     Pounds  of  fat  in  I  to  10,000  Ibs.  of  milk  (Continued). 


1 

4.20 

4.25 

4.30 

4.35 

4.40 

4.45 

4.50 

4.55 

4.60 

4.65 

4.70 

4.75 

I 

Milk 

Milk 

Ibs. 

Ibs. 

10,000 

420 

425 

430 

435 

440 

446 

450 

455 

460 

465 

470 

475 

10,000 

9,000 

378 

383 

387 

392 

396 

401 

405 

410 

414 

419 

423 

428 

9,000 

8,000 

336 

340 

344 

348 

352 

356 

360 

364 

368 

372 

376 

380 

8,000 

7,000 

294 

298 

301 

305 

308 

312 

315 

319 

322 

326 

329 

383 

7,000 

ti.OOO 

252 

255 

258 

261 

264 

267 

270 

273 

276 

279 

282 

285 

6,000 

5,000 

210 

213 

215 

218 

220 

223 

225 

228 

230 

233 

235 

238 

5.0CO 

4,000 

168 

170 

172 

174 

176 

178 

180 

182 

184 

186 

188 

190 

4,000 

3,000 

126 

128 

129 

131 

132 

134 

135 

137 

138 

140 

141 

143 

3,000 

2,000 

84.0 

85.0 

86.0 

87.0 

88.0 

89.0 

90.0 

91.0 

92.0 

93.0 

94.0 

95.0 

2,000 

1,000 

42.0 

42.5 

43.0 

43.5 

44.0 

44.5 

45.0 

45.6 

46.0 

46.5 

47.0 

47.5 

1,000 

900 

37.8 

38.3 

38.7 

39.2 

39.6 

40.1 

40.5 

41.0 

41.4 

41.9 

42.3 

42.8 

900 

800 

33.6 

31.0 

34.4 

34.8 

35.2 

35.6 

36.0 

36.4 

36.8 

37.2 

37.6 

38.0 

800 

700 

29.4 

29.8 

30.1 

30.5 

30.8 

31.2 

31.5 

31.9 

32.2 

32.6 

32.9 

33.3 

700 

600 

2-5.2 

25.5 

•?5.8 

26.1 

26.4 

26.7 

27.0 

27.3 

27.6 

27.9 

28.2 

28.5 

600 

500 

21.0 

21.3 

21.5 

21.8 

22.0 

22.3 

22.5 

22.8 

23.0 

23.3 

23.5 

23.8 

500 

400 

16.8 

17.0 

17.2 

17.4 

17.6 

17.8 

18.0 

18.2 

18.4 

18.6 

18.8 

19.0 

400 

300 

12.6 

12.8 

12.9 

13.1 

lo  2 

13.4 

13.5 

13.7 

13.8 

14.0 

14.1 

14.3 

300 

200 

8.4 

8.5 

8.6 

8.7 

8.8 

8.9 

9.0 

9.1 

9.2 

9.3 

9.4 

9.5 

2<M) 

100 

4.2 

4.3 

4.3 

4.4 

4.4 

4.6 

4.5 

4.6 

4.6 

4.7 

4.7 

4.8 

100 

90 

3.8 

3.8 

3.9 

3.9 

4.0 

4.0 

4.1 

4.1 

4.1 

4.2 

4.2 

4.3 

90 

80 

3.4 

3.4 

3.4 

3.5 

3.5 

3.6 

3.6 

3.6 

3.7 

3.7 

3.8 

3.8 

KO 

70 

2.9 

3.0 

3.0 

3  0 

3.1 

3.1 

3.2 

3.2 

3.2 

3.3 

3.3 

3.3 

70 

60 

2.5 

2.6 

2.6 

2.6 

2.6 

2.7 

2.7 

2.7 

2.8 

2.8 

2.8 

2.9 

'50 

50 

2.1 

2.1 

2.2 

2.2 

2.2 

2.2 

2.3 

2.3 

2.3 

2.3 

2.4 

2.4 

50 

40 

on 

1.7 

1.7 

10 

1.7 

10 

1.7 

10 

1.8 

10 

1.8 

10 

1.8 

1.8 

1.8 

1.9 

1.9 

1.9 

40 

on 

oU 
20 

1  .3 
.8 

.6 

.9 

.0 

.9 

.0 

.9 

.O 

.9 

.0 

.9 

.9 

.9 

.9 

.9 

.9 

1.0 

oU 

20 

10 

.4 

.4 

.4 

.4 

.4 

.4 

.5 

.6 

.5 

.6 

.5 

.6 

10 

8 
7 

•^ 

•^ 

•^ 

3 

4 

4 

4 

4 

4 

4 

4 

4 

8 
7 

o 

3 

3 

3 

3 

3 

3 

3 

3 

3 

6 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

6 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

2 

2 

2 

91 

•  2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

^ 

3 

1 

1 

1 

.1 

1 

1 

1 

1 

1 

1 

3 

2 

1 

1 

1 

1 

1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

1 

4.30 

4.35 

4.45 

4.50 

4.55 

4.60 

4.65 

4.70 

4.75 

1 

4.20 

4.25 

4.40 

? 

270  Testing  Milk  and  Its  Products. 

Table  VII.    Pounds  of  fat  in  I  to  10.000  Ibs.  of  milk  (  Continued). 


J 

4.80 

4.85 

4.90 

4.95 

5.00 

5.05 

5.10 

5.15 

5.20 

5.25 

5.30 

5.35 

i 

Milk 

Milk 

Iba. 

Ibs. 

10,000 

480 

485 

490 

495 

500 

505 

510 

515 

520 

525 

530 

535 

10,000 

9,000 

432 

437 

441 

446 

450 

455 

459 

4Q4 

468 

473 

477 

482 

9,000 

8,000 

384 

388 

392 

3U6 

400 

404 

408 

412 

416 

420 

424 

428 

8,000 

7,000 

336 

340 

343 

347 

350 

354 

357 

361 

364 

368 

371 

375 

7,000 

6,000 

288 

291 

294 

297 

300 

303 

306 

309 

312 

315 

318 

321 

6,000 

5,000 

240 

243 

245 

248 

250 

253 

255 

258 

260 

263 

265 

268 

5,000 

4,000 

192 

194 

196 

198 

200 

202 

204 

206 

208 

210 

212 

214 

4,000 

3,000 

144 

146 

147 

149 

150 

152 

153 

155 

156 

158 

159 

161 

3,000 

•2,000 

96.0 

97.0 

98.0 

99.0 

100 

101 

102 

103 

104 

105 

106 

107 

2,000 

1,000 

48.0 

48.5 

49.0 

49.5 

50.0 

50.5 

51.0 

51.5 

52.0 

52.5 

53.0 

53.5 

1,000 

900 

43.2 

43.7 

44.1 

44.6 

45.0 

45.5 

45.7 

46.4 

46.8 

47.3 

47.7 

48.2 

900 

800 

38.4 

38.8 

39.2 

39.6 

40.0 

40.4 

40.8 

41.2 

41.6 

42.0 

42.4 

42.8 

800 

700 

33.6 

34.0 

34.3 

34.7 

35.0 

35.4 

35.7 

36.1 

36.4 

36.8 

37.1 

37.5 

700 

600 

28.8 

29.1 

29.4 

29.7 

30.0 

30.3 

30.6 

30.9 

31.2 

31.5 

31.8 

32.1 

600 

500 

24.0 

24.3 

24.5 

24.8 

25.0 

25.3 

25.5 

25.8 

26.0 

26.3 

26.5 

26.8 

500 

400 

19.2 

19.4 

19.6 

19.8 

20.0 

20.2 

20.4 

20.6 

20.8 

21.0 

21.2 

21.4 

400 

300 

14.4 

14.6 

14.7 

14.9 

15.0 

15.2 

15.3 

15.5 

15.6 

15.8 

15.9 

16.1 

300 

200 

9.6 

9.7 

9.8 

9.9 

10.0 

10.1 

10.2 

10.3 

10.4 

10.5 

10.6 

10.7 

200 

100 

f\f\ 

4.8 

4.9 

4.9 

5.0 

5.0 

6.1 

5.1 

6.2 

5.2 

5.3 

5.3 

5.4 

100 

f\f\ 

yu 
80 
70 

3.8 
3.4 

3.9 
3.4 

3.9 
3.4 

4.0 
3.5 

4.0 
8.5 

4.0 
8.5 

4.1 
3.6 

4.1 
3.6 

4.2 
3.6 

4.2 
3.7 

4.2 
3.7 

4.3 
3.7 

yu 
80 
70 

60 

2.9 

2.9 

2.9 

3.0 

3.0 

3.0 

3.1 

3.1 

3.1 

3.2 

3.2 

3.2 

60 

50 

2.4 

2.4 

2.5 

2.5 

2.5 

2.5 

2.6 

2.6 

2.6 

2.6 

2.7 

2.7 

50 

40 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

2.1 

2.1 

2.1 

40 

30 

1.4 

1.5 

1.5 

1.6 

1.5 

1.5 

1.5 

1.5 

1.6 

1.6 

1.6 

1.6 

30 

20 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

1.1 

20 

10 

.5 

5 

5 

5 

5 

5 

fS 

f> 

5 

5 

5 

5 

10 

9 

.4 

.4 

.4 

.4 

.5 

.6 

.5 

.5 

.5 

.5 

.5 

.5 

9 

8 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

8 

y 

^ 

T 

T 

^ 

4 

4 

4 

4 

4 

4 

4 

4 

7 

6 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

G 

5 

.2 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

5 

4 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

.1 

.1 

.1 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

3 

2 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

•  .1 

2 

1 

1 

.1 

.1 

1 

1 

1 

1 

1 

1 

5.20 

j 

4.80 

4.85 

4.90 

4.95 

5.00 

5.05 

5.10 

5.15 

5.25 

5.30 

5.35 

I 

Appendix. 


271 


Table  VIII.     Pounds  of  fat  in  I  to  1000  Ibs.  of  cream  testin§ 
12.0  to  50.0  per  tent.  fat. 

(See  directions  for  use,  p.  266  ) 


1 

12 

18 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

1000 

120 

180 

140 

150 

160 

170 

180 

190 

200 

210 

220 

230 

240 

250 

260 

270 

280 

290 

800 

900 

108 

117 

126 

135 

144 

153 

162 

171 

180 

189 

198 

207 

216 

225 

234 

248 

252 

261 

270 

800 

96 

104 

112 

120 

128 

186 

144 

152 

160 

168 

176 

184 

192 

200 

208 

216 

224 

232 

240 

700 

84 

91 

98 

105 

112 

119 

126 

133 

140 

147 

154 

161 

168 

175 

182 

189 

196 

203 

210 

800 

72 

78 

84 

90 

96 

102 

108 

114 

120 

126 

182 

138 

144 

150 

156 

162 

168 

174 

180 

600 

00 

66 

70 

75 

80 

85 

90 

95 

100 

105 

110 

115 

1201 

125 

130 

1351 

140 

145 

150 

400 

48 

62 

66 

60 

64 

68 

72 

76 

80 

84 

88 

92 

96 

100 

104 

108 

112 

116 

120 

MO 

88 

39 

42 

45 

48 

61 

64 

57 

60 

63 

66 

69 

72 

75 

78 

81 

84 

87 

90 

900 

24 

26 

28 

82 

84 

86 

88 

40 

42 

44 

46 

48 

50 

62 

54 

66 

68 

60 

100 

12 

18 

14 

16 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

80 

90 
80 

10.8 
9.6 

11.7 
10.4 

12.6 
11.2 

11.5 

12.0 

14.4 

12.8 

15.3 
13.6 

16.2 

14.4 

17.1 
15.2 

18.0 
16.0 

18.9 
16.8 

19.8 
17.6 

20.7 
18.4 

21.6 

19.2 

22.5 
20.0 

23.4 
20.8 

24.8 
21.6 

25.2 
22.4 

26.1 
23.2 

27.0 
24.0 

TO 

8.4 

9.1 

9.8 

10.5 

11.2 

11.9 

12.6 

13.3 

14.0 

14.7 

15.4 

16.1 

16.8 

17.5 

18.2 

18.9 

19.6 

20..3 

21.0 

00 

7.2 

7.8 

8.4 

9.0 

9.6 

10.2 

10.8 

11.4 

12.0 

12.6 

13.2 

13.8 

14.4 

15.0 

15.6 

16.2 

16.8 

17.4 

18.0 

60 

6.0 

8.5 

7.0 

7.5 

8.0 

8.5 

9.0 

9.5 

10.0 

10.5 

11.0 

11.5 

12.0 

12.6 

13.0 

13.6 

14.0 

14.5 

15.0 

<0 

4.8 

5.6 

6.0 

6.4 

6.8 

7.2 

7.6 

8.0 

8.8 

9.2 

9.6 

10.0 

10.4 

10.8 

11.2 

11.6 

12.0 

80 

8.6 

8  9 

4.2 

4.5 

4.8 

6.1 

5.4 

5.7 

6.0 

9  3 

6.6 

6.9 

7.2 

7.5 

7.8 

8.1 

8.4 

8.7 

e.o 

90 

2.4 

2.6 

2.8 

3.0 

8.2 

8.4 

8.6 

3.8 

4.0 

4.2 

4.4 

4.6 

4.8 

6.0 

5.2 

6.4 

5.6 

6.8 

6.0 

10 

l.f 

1.8 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

2.1 

2.2 

2.3 

2.4 

2.5 

2.6 

2.7 

2.8 

2.9 

8.0 

9 

1.08 

1.17 

1.26 

1.85 

1.44 

1.58 

1.62 

1.71 

1.80 

1.89 

1.98 

2.07 

2.16 

2.25 

2.34 

1.48 

2.52 

2.61 

2.70 

g 

.96 

1.04 

1.12 

1.20 

1.28 

1.36 

1.44 

1.52 

1.60 

1.68 

1.76 

1.84 

1.92 

2.00 

2.08 

2.16 

2.24 

2.32 

2.40 

j 

.84 

.91 

.98 

1.05 

1.12 

1.19 

1.26 

1.33 

1.40 

1.47 

1.54 

1.61 

l.«8 

1.75 

1.82 

1.89 

1.96 

2.03 

2.10 

1 

.72 

.78 

.84 

.90 

.96 

1.02 

1.08 

1.14 

1.20 

1.26 

1.32 

1.88 

1.44 

1.50 

1.56 

1.62 

1.68 

1.74 

1.80 

i 

.00 

.65 

.70 

.75 

.80 

.85 

.90 

,95 

1.00 

1.05 

1.10 

1.15 

1.20 

1.25 

1.30 

1.35 

1.40 

1.45 

1.50 

.48 

.52 

.56 

.60 

.64 

.68 

.72 

.76 

.80 

.84 

.88 

.92 

1.00 

1.04 

1.08 

1.12 

1.16 

1.20 

1 

.80 

.89 

.42 

.46 

.48 

.51 

.64 

.67 

.60 

.63 

.66 

.69 

.72 

.75 

.78 

.81 

.84 

.87 

.90 

.24 
.12 

.26 
.18 

.28 
.14 

.80 
.15 

.82 
.16 

.84 
.17 

.86 
.18 

:!S 

:£ 

.42 
.21 

£ 

£ 

£ 

:8 

.52 
.26 

.54 
.27 

£ 

£ 

.00 

M 

272 


Testing  Milk  and  Its  Products. 


Table  Vltl.    Pounds  of  fat  in  I  to  1000  Ibs.  of  cream  (continued}. 


1 

81 

82 

33 

84 

85 

86 

87 

88 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

69 

II 

1000 

810 

820 

380 

940 

350 

860 

870 

880 

390 

400 

410 

420 

480 

440 

450 

460 

470 

490 

490 

500 

900 

279 

288 

297 

306 

315 

824 

833 

342 

351 

360 

869 

378 

887 

896 

405 

414 

423 

482 

441 

450 

800 

248 

256 

264 

272 

280 

288 

296 

304 

312 

820 

328 

336 

344 

352 

860 

368 

876 

884 

892 

400 

700 

217 

224 

231 

238 

245 

252 

259 

266 

273 

280 

287!  294 

301 

308 

315 

329 

886 

850 

600 

186 

192 

198 

204 

210 

216 

222 

228 

234 

240 

246  252 

258 

264 

270 

276 

282 

288 

294 

300 

500 

165 

160 

165 

170 

175 

180 

185 

190 

195 

200 

2051  210 

215 

220 

225 

230 

235 

240 

245 

250 

400 

124 

128 

132 

136 

140 

144 

148 

152 

156 

160 

164 

168 

172 

176 

180 

184 

188 

192 

196 

200 

93 

96 

99 

102 

106 

108 

111 

114 

117 

120 

128 

126 

129 

132 

135 

188 

141 

144 

147 

150 

100 

62 

64 
82 

66 
33 

68 
34 

70 
86 

72 
36 

74 
87 

76 
38 

78 

80 

82 

84 

86 

88 

90 

92 

94 

96 

98 

100 

90 

27.9 

28.8 

29.7 

30.6 

81.5 

82.4 

38.8 

34.2 

35.1 

86.0 

36.9 

87.8 

38.7 

39.6 

40.5 

41.4 

42.3 

48.2 

44.1 

45.0 

80 

24.8 

25.6 

26.4 

27.2 

28.0 

28.8 

29.6 

30.4 

21.2 

82.0 

32.8 

33.6 

34.4 

35.2 

86.0 

86.8 

37.6 

88.4 

.39.2 

40.0 

70 
60 

21.7 
18.6 

22.4 
19.2 

23.1 
19.8 

23.8 
20.4 

24.5 
21.0 

25.2 
21.6 

25.9 

22.2 

26.6 
22.8 

27.8 
28.4 

28.0 
24.0 

28.7 
24.6 

29.4 
25.2 

30.1 
25.8 

SO.  8 

26.4 

31.6 
27.0 

32.2 
27.6 

82.9 
28.2 

33.6 

28.8 

84.3 
29.4 

35.0 
30.0 

50 

15.5 

16.0 

16.5 

17.0 

17.5 

18.0 

18.5 

19.0 

19.5 

20.0 

20.6 

21.0 

21.5 

22.0 

22.6 

23.0 

23.6 

24.0 

24.6 

25.0 

£ 

12.4 
9.8 

12.8 
9.6 

13.2 
9.9 

13.6 
10.2 

14.0 
10.5 

14.4 
10.8 

14.8 
11.1 

15.2 
11.4 

15.6 
11.7 

16.0 
12.0 

16.4 
12.8 

16.8 
12.6 

17.2 
12.9 

17.6 
13.2 

18.0 
18.5 

18.4 
18.8 

18.8 
14.1 

19.2 
14.4 

19.6 
14.7 

20.0 
15.0 

30 

6.2 

6.4 

6.6 

6.8 

7.0 

7.2 

7.4 

7.6 

7.8 

8.0 

8.2 

8.4 

8.6 

8.8 

9.0 

9.2 

9.4 

9.6 

9.8 

10.0 

10 

3.1 

8.8 

8.4 

8.5 

8.6 

».7 

3.8 

8.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5 

4.6 

4.7 

4.8 

4.9 

6.0 

9 

2.79 

2.88 

2.97 

3.06 

3.15 

3.24 

8.88 

3.42 

8.51 

8.60 

8.69 

8.78 

3.87 

8.96 

4.95 

4.14 

4.28 

4.82 

4.41 

4.50 

8 

7 

2.48 
2.17 

2.56 
2.24 

2.64 
2.81 

2.72 
2.38 

2.80 
2.45 

2.88 
2.52 

2.96 
2.59 

3.04 
2.66 

3.12 
2.73 

3.20 
2.80 

3.28 
2.87 

8.86 
2.94 

3.44 
5.01 

3.52 
3.08 

8.60 
8.15 

3.68 
3.22 

8.76 
3.29 

3.84 
8.86 

3.924.00 
8.  433.50 

E 

1.86 
1.55 

1.92 
1.60 

1.98 
1.65 

2.04 
1.70 

2.10 
1.75 

2.16 
1.80 

2.22 
1.85 

2.28 
1.90 

2.34 
1.95 

2.40 
2.00 

2.48 
2.05 

2.62 
2.10 

2!  15 

2,64 

2.702.76 
2.252.80 

2.82 
2.35 

2.88 
2.40 

2.948.00 
2.45J2.50 

4 

1.24 

1.28 

1.82 

1.36 

1.40 

1.44 

1.48 

1.52 

1.56 

1.60 

1.64 

1.68 

1.72 

U76 

1.801.84 

1.88 

1.92 

1.062.00 

8 

.96 

.99 

1.02 

1.05 

1.08 

1.11 

1.14 

1.17 

1.20 

1.28 

1.26 

1.29 

1.32 

1.361.88 

1.41 

1.44 

1.471.  GO 

2 

'.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

.82 

.84 

.86 

.88 

.90  .92 

.94 

.96 

.981.00 

1 

.SI 

.82 

.34 

.36 

.86 

.87 

.88 

.89 

.40 

.41 

.42 

.48 

.44 

.45  .46 

.47 

.48 

Appendix. 


Amount  due  for  butter  fat,  in  dollars  and  cents,  at 
12  to  25  cents  per  pound. 

(See  directions  for  use,  page  £((.) 


3 

•o 

M. 

Pounds  of  builcr  fat. 

§3 

j.o 

'•a 
H  c 

1 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

» 

11 

12 

120.00 

108.00 

96.00 

84.00 

72.00 

60.00 

48.00 

36.00 

$ 

24.00 

$ 

12.00 

12 

12J 

122.50 

110.25 

98.00 

85.75 

73.50 

61.25 

49.00 

36.75 

24.50 

12.25 

-1 

12J 

125.00 

112.50 

100.00 

87.50 

75.00 

62.50 

50.00 

37.50 

25.00 

12.50 

2J 

12$ 

127.50 

114.75 

102.00 

89.25 

76.50 

63.75 

51.00 

38.25 

25.50 

12.75 

-I 

13 

130.00 

117.00 

104.00 

91.00 

78.00 

65.00 

52.00 

39.00 

26.00 

13.00 

3 

131 

132.50 

119.25 

106.00 

92.75 

79.50 

66.25 

53.00 

39.75 

26.50 

13.25 

sj 

13  J 

135.00 

121.50 

108.00 

94.50 

81.00 

67.50 

54.00 

40.50 

27.00 

13.50 

:U 

13| 

137.50 

123.75 

110.001  96.25 

82.50 

68.75 

55.00 

41.25 

27.50 

13.75 

13J 

14 

140.00 

126.00 

112.00   98.00 

84.00 

70.00 

56.00 

42.00 

28.00 

14.00 

4 

141 

142.50 

128.25 

114.00   99.75 

85.50 

71.2-5 

57.00 

42.75 

28.50 

14.2-5 

q 

14i 

145.00 

130.50 

116.001101.  50 

87.00 

72.50 

58.00 

43.50 

29.00 

14.50 

4J 

wi 

147.50 

132.75 

118.00 

103.25 

88.50 

73.75 

59.00 

44.25 

29.50 

14.75 

1*3 

15 

150.00 

135.00 

120.00 

105.00 

90.00 

75.00 

60.00 

45.00 

30.00 

15.00 

15 

151 

152.50 

137.25 

122.00 

106.75 

91.50 

76.25 

61.00 

45.75 

30.50 

15.25 

151 

154 

155.00 

139.50 

124.00 

108.50 

93.00 

77.50 

62.00 

46.50 

31.00 

15.50 

loj 

16| 

157.50 

141.75 

126.00 

110.25 

94.50 

78.7563.00 

47.25 

31.50 

15.75 

1,31 

16 

160.00 

144.00 

128.00 

112.00 

96.00 

80.00 

64.00 

48.00 

32.00 

16.00 

16 

161 

162.50 

146.25 

130.00 

113.75 

97.50 

81.25 

65.00 

48.75 

32.50 

16.25 

161 

16] 

165.00 

148.50 

132.00 

115.50 

99.00 

82.50 

66.00 

49.5033.00 

16.50 

LBi 

163 

167.50 

150.75 

134.00 

117.25 

100.50 

83.75 

67.00 

50.25 

33.50 

16.75 

16| 

17 

170.00 

153.00 

136.00 

119.00 

102.00 

85.00 

68.00 

51.0034.00 

17.00 

17 

17} 

172.50 

155.25 

138.00 

120.75 

103.50 

86.25 

69.00 

51.7534.50 

17.25 

171 

17) 

IT) 

175.00 
177.50 

157.50 
159.75 

140.00 
142.00 

122.50 
124.25 

105.0087.50 
106.5087.75 

70.00 
71.00 

52.50i35.00 
53.2535.50 

17.50 

17.75 

17* 
173 

18 

180.00 

162.00 

144.00 

126.00 

108.0090.00 

72.00 

54.00136.00 

18.00 

18 

18  ', 

182.50 

164.25 

146.00 

127.75 

109.5091.25 

73.00 

54.  75136.50 

18.25 

IS* 

18  i 

185.00 

166.50 

148.00  129.50 

111.00,92.50 

74.00 

55.5037.00 

18.50 

18} 

18| 

187.50 

168.75 

150.00131.25 

112.50 

93.75 

75.00|56^25 

3-  50 

18.75 

18J 

1,000 

900 

800       700 

600 

500 

400     300 

2UO 

100 

274 


Testinn  M*lk  and  Its  Products. 


IX.       Amount  due  for  butter  fat  (Continued}. 


Price  per  | 
pound,  cenU. 

Pounds  of  butter  fut. 

P 

19 
19J 
19i 
19? 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

19 
19* 
19} 
195 

190.00 
192.50 
195.00 
197.50 

171.00 
173.25 
175.50 
177.75 

152.00 
154.00 
156.00 
158.00 

133.00 
134.75 
136.50 
138.25 

114.00 
115.50 
117.00 
118.50 

95.00 
96.25 
97.50 
98.75 

76.00 
77.00 
78.00 
79.00 

57.00 
57.75 
58.50 
59.25 

38.00 
38.50 
39.00 
39.50 

19.00 
19.25 
19.50 
19.75 

20 

3 

205 

200.00 
202.50 
205.00 
207.50 

180.00 
182.25 
184.50 
186.75 

160.00 
162.00 
164.00 
166.00 

140.00 
141.75 
143.50 
145.25 

120.00 
121.50 
123.00 
124.50 

100.00 
101.25 
102.50 
103.75 

80.00 
81.00 
82.00 
83.00 

60.00 
60.75 
61.50 
62.25 

40.00 
40.50 
41.00 
41.50 

20.00 
20.25 
20.50 
20.75 

20 
20J 

st 

21 
21i 
21j 
21J 

210.00 
212.50 
215.00 
217.50 

189.00 
191.25 
193.50 
195.75 

168.00 
170.00 
172.00 
174.00 

147.00 
148.75 
150.50 
152.25 

126.00 
127.50 
129.00 
130.50 

105.00 
106.25 
107.50 
108.75 

84.00 
85.00 
86.00 
87.00 

63.00 
63.75 
64.50 
65.25 

42.00 
42.50 
43.00 
43.50 

21.00 
21.25 
21.50 
21.75 

21 
211 

21  J 

213 

22 

I 

220.00 
222.50 
225.00 
227.50 

198.00 
200.25 
202.50 
204.75 

176.00 
178.00 
180.00 
182.00 

154.00 
155.75 
157.50 
159.25 

132.00 
133.50 
135.00 
136.50 

110.00 
111.25 
112.50 
113.75 

88.00 
89.00 
90.00 
91.00 

66.00 
66.75 
67.50 
68.25 

44.00 
44.50 
45.00 
45.50 

22.00 
22.25 
22.50 
22.75 

22 
221 
224 

22| 

23 
23* 
23* 
23} 

230.00 
232.50 
235.00 
237.50 

207.00 
209.25 
211.50 
213.75 

184.00 
186.00 
188.00 
190.00 

161.00 
162.75 
164.50 
166.25 

138.00 
139.50 
141.00 
142.50 

115.00 
116.25 
117.50 
118.75 

92.00 
93.00 
94.00 
95.00 

69.00 
69.75 
70.50 
71.25 

46.00 
46.50 
47.00 
47.50 

23.00 
23.25 
23.50 
23.75 

23 
23J 
23* 
23| 

24 

ill 

y 

240.00 
242.50 
245.00 
247.50 
250.00 

216.00 
218.25 
220.50 
222.75 
225.00 

192.00 
194.00 
196.00 
198.00 
200.00 

168.00 
169.75 
171.50 
173.25 
175.00 

144.00 
145.50 
147.00 
148.50 
150.00 

120.00 
121.25 
122.50 
123.75 
125.00 

96.00 
97.00 
98.00 
99.00 
100.00 

72.00 
72.75 
73.;>0 
74.25 
75.00 

48.00 
48.50 
49.00 
49.50 
50.00 

24.00 
24.25 
24.50 
24.75 
25.00 

24 
243 
241 

24$ 
25 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

Appendix. 


275 


Table  X.     Relative-value  tables. 

(See  directions  for  use,    par.  238.) 


ll 

3.0 
3.1 
3.2 
3.3 
3.4 

8.5 
3.6 

R  7 

Price  of  milk  per  100  pounds,  In  dollars  and  cents. 

.30 
.31 
.32 
.33 
.34 

.35 

.36 
37 

.31 
.33 
.34 
.35 
.36 

.37 

.38 
.39 

.33 
.34 
.35 
.36 
.37 

.38 
.40 
41 

.34 

.36 
.37 

.38 
.39 

.40 
.41 
.43 

.36 
.37 

.38 
.40 
.41 

.42 
.43 
44 

.37 
.39 
.40 
.41 
.42 

.44 

.45 
46 

.39 
.40 
.42 
.43 
.44 

.45 

.47 

48 

.40 

.42 
.43 
.45 
.46 

.47 
.49 
.50 

.42 
.43 
.45 
.46 

.48 

.49 
.60 
.52 

.43 
.45 
.46 
.48 
.49 

.61 

.52 
54 

.45 
.46 
.4f- 
.46 
.61 

.6£ 
.54 

fifi 

3.8 
3.9 

4  0 

.38 
.39 

40 

.40 
.41 

42 

.42 
.43 

44 

.44 
.45 

46 

.46 
.47 

48 

.47 
.49 

50 

.49 
.51 

52 

.51 
.53 

54 

.53 
.55 

56 

.55 
.57 

58 

.57 
.68 

6f 

4  1 

41 

43 

45 

.47 

49 

51 

53 

55 

57 

59 

61 

4.2 

H 

4.5 
4.6 
4.7 
4.8 
4.9 

5.0 

5.1 
5.2 
5.3 

5  4 

.42 

.44 

46 

48 

50 

52 

.55 

.57 

59 

61 

6? 

.43 

44 

.45 
.46 

.47 
48 

.49 
51 

.52 
.53 

.54 
55 

.56 
.67 

.58 
.59 

.60 
.62 

.62 
.64 

.64 

6<: 

.45 

.47 

.49 

.52 

.54 

.56 

.58 

.61 

.63 

.65 

6: 

.46 
.47 
.48 
.49 

.50 
.51 
.52 
.53 
54 

.48 
.49 
.50 
.51 

.62 
.54 
.55 
.56 
.57 

.51 
.52 
.53 
.54 

.55 

.56 
.57 
.58 
59 

.53 
.54 
.55 
.66 

.57 

.59 
.60 
.61 
62 

.55 
.56 
58 
.59 

.60 
.61 
.62 
.64 
65 

.57 
.59 
.60 
.61 

.62 
.64 
.65 
.66 
67 

.60 
.61 
.62 
.64 

.65 
.66 
.68 
.69 
70 

.62 
.63 
.65 
.66 

.67 
.69 
.70 

.72 
73 

.64 
.66 
.67 
.69 

.70 
.71 
.73 
.74 

76 

.67 
.68 
.70 
.71 

.72 
.74 
.75 

.77 
.78 

.6^ 
.7C 

.72 
.73 

.75 
.7C 
.78 
.79 
81 

5.5 
5.6 
5.7 

.55 

.56 
57 

.58 
.59 
60 

.60 
.62 
63 

.63 
.64 
66 

.66 
.67 

68 

.69 
.70 
71 

.71 
.73 
.74 

.74 

.76 
.77 

.77 
.78 

.80 

.80 
.81 
.83 

.8$ 
.84 
8fi 

5.8 
5.9 
6.0 

.58 
.59 
.60 

.61 
.62 
.63 

.64 
.65 
.66 

.67 
.68 
.00 

.70 
.71 
.72 

.72 
.74 
.75 

.75 

.77 
.78 

.78 
.80 
.81 

.81 
.83 

.84 

.84 
.86 
.87 

.87 
.88 
.90 

276 


Testing' Milk  and  Its  Products. 


Table   X.    Relative-value  tables  ( Continued). 


3 

li 

Price  of  milk  per  100  pounds,  In  dollar*  and  cents. 

8.0 

.46 

.48 

.49 

.51 

.52 

.54 

.55 

.57 

.58 

.60 

8.1 

.48 

.50 

.51 

.53 

.54 

.56 

.57 

.69 

.60 

.62 

8.2 

.50 

.51 

.53 

.54 

.56 

.58 

.59 

.61 

.62 

.64 

3.3 

.51 

.53 

.54 

.56 

.58 

.59 

.61 

.63 

.64 

.66 

8.4 

.63 

.54 

.56 

.58 

.59 

.61 

.63 

.65 

.66 

.68 

8.5 

.64 

.66 

.68 

.69 

.61 

.63 

.65 

.66 

.68 

.70 

.6 

.66 

.68 

.69 

.CL 

.68 

.66 

.67 

.68 

.70 

.72 

.7 

.67 

.69 

.61 

.68 

.66 

.67 

.68 

.70 

.72 

.74 

.8 

» 

.61 

.68 

.66 

.66 

.68 

.70 

.72 

.74 

.76 

.9 

.60 

.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.0 

.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

.1 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

.82 

.2 

.65 

.67 

.69 

.71 

.73 

.76 

.78 

.80 

.82 

.84 

.3 

.67 

.69 

.71 

.73 

.75 

.77 

.80 

.82 

.84 

.86 

.4 

.68 

.70 

.73 

.75 

.77 

.79 

.81 

.84 

.86 

.88 

.5 

.70 

.72 

.74 

.76 

.79 

.81 

.83 

.85 

.88 

.90 

ft 

.71 

.74 

.76 

.78 

.80 

.83 

.85 

.87 

.90 

92 

7 

.73 

.75 

.78 

.80 

.82 

.85 

.87 

.89 

.92 

94 

.8 

.74 

.77 

.79 

.82 

.84 

.86 

.89 

.91 

.94 

.96 

4.9 

.76 

.78 

.81 

.83 

.86 

.88 

.91 

.98 

.96 

.98 

5.0 

.77 

.80 

.82 

.85 

.87 

.90 

.92 

.95 

.97 

1.00 

6.1 

.79 

.82 

.84 

.87 

.89 

.92 

.94 

.97 

.99 

1.02 

6.2 

.81 

.83 

.86 

.88 

.91 

.94 

.96 

.99 

1.01 

1.04 

6.3 

.83 

.85 

.87 

.90 

.93 

.95 

.98 

1.01 

1.03 

1.06 

6.4 

.84 

.86 

.89 

.92 

.94 

.97 

1.00 

1.03 

1.05 

1.08 

6.5 

.85 

.88 

.91 

.93 

.96 

.99 

1.02 

1.04 

1.07 

1.10 

5.6 

.87 

.90 

.92 

.95 

.98 

1.01 

1.04 

1.06 

1.09 

1.12 

5.7 

.88 

.91 

.94 

.97 

1.00 

1.03 

1.05 

1.08 

1.11 

1.14 

5.8 

.90 

.93 

.96 

.99 

1.01 

1.04 

1.07 

1.10 

1.13 

1.16 

5.9 

.91 

.94 

.97 

1.00 

1.03 

1.06 

1.09 

1.12 

1.15 

1.18 

6.0 

.93 

.96 

.99 

1.02 

1.05 

1.08 

1.11 

1.14 

1.17 

1.20 

Appendix. 


277 


Table   X.    Relative-value  tables  (Continued). 


1* 

Price  of  milk  per  100  pounds,  in  dollars  and  cento. 

3.0 

.61 

.63 

.64 

.66 

.67 

.69 

.70 

.72 

.73 

75 

8  1 

.64 

.65 

.67 

.68 

.70 

.71 

.73 

.74 

76 

78 

3.2 

.66 

.67 

.69 

.70 

.72 

.74 

.75 

.77 

.78 

.80 

3.3 

.68 

.69 

.71 

.73 

.74 

.76 

.78 

.79 

.81 

83 

3  4 

.70 

.71 

.73 

.75 

.76 

.78 

.80 

.82 

83 

85 

3.5 

.72 

.73 

.75 

.77 

.79 

.80 

.82 

.84 

.86 

.88 

3.6 

.74 

.76 

.77 

.79 

.81 

.83 

.85 

.86 

.88 

.90 

3.7 

.76 

.78 

.80 

.81 

.83 

.85 

.87 

.89 

.91 

.93 

3.8 

.78 

.80 

.82 

.84 

.85 

.87 

.89 

.91 

.93 

.95 

3.9 

.80 

.82 

.84 

.86 

.88 

.90 

.92 

.94 

.96 

.98 

4.0 

.82 

.84 

.86 

.88 

.90 

.92 

.94 

.96 

.98 

.00 

4.1 

.84 

.86 

.88 

.90 

.92 

.94 

.96 

.98 

1.00 

03 

4.2 

.86 

.88 

.90 

.92 

.94 

.97 

.99 

.01 

1.03 

05 

4  3 

88 

90 

92 

.95 

97 

99 

1  01 

03 

1  05 

08 

4.4 

.90 

.92 

.95 

.97 

.99 

1.01 

1.03 

.06 

1.08 

.10 

4  5 

92 

.94 

97 

.99 

1  01 

1  03 

1  06 

08 

1  10 

.13 

4.6 

.94 

.97 

.99 

1.01 

.03 

1.06 

1.08 

.10 

1.13 

.15 

4  7 

96 

99 

1  01 

.03 

.06 

1.08 

1  10 

13 

1  15 

18 

4  8 

98 

1.01 

1  03 

1  06 

.08 

1.10 

1  13 

15 

1  18 

20 

4.9 

1.00 

1.03 

1.05 

.08 

.10 

1.13 

1.15 

.18 

1.20 

.23 

5.0 

1.02 

1.05 

1.07 

1.10 

.12 

.15 

1.18 

.20 

1.23 

.25 

5  1 

1  05 

1  07 

1  10 

.12 

.15 

.17 

1  20 

22 

1.25 

27 

5.2 

1.07 

1.09 

1.12 

.14 

.17 

.20 

1.22 

.25 

1.27 

.30 

5.3 

.09 

1.11 

1.14 

.17 

.19 

.22 

1.25 

.27 

1.30 

.32 

5.4 

.11 

1.13 

1.16 

.19 

.21 

.24 

1.27 

.30 

1.32 

.35 

5.5 

.13 

1.15 

1.18 

.21 

.24 

.26 

1.29 

.32 

1.35 

.38 

5.6 

.15 

1.18 

1  l>0 

.23 

.26 

.29 

1.32 

.34 

1.37 

.40 

5.7 

.17 

1.20 

1.23 

.25 

.28 

.31 

1.34 

.37 

1.39 

.43 

5.8 

.19 

1.22 

1.25 

.28 

.30 

.33 

1.36 

.39 

1.42 

.45 

5.9 

.21 

1.24 

1.27 

.30 

.33 

.36 

1.39 

.42 

1.45 

.48 

6.0 

.23 

1.26 

1.29 

.32 

.35 

.38 

1.41 

.44 

1.47 

.50 

273 


Testing  Milk  and  Its  Products. 


Table   X.    Relative-value  tables  (Continued). 


q 
3  0 

Price  of  milk  per  100  pounds,  In  dollars  and  cents. 

76 

78 

79 

81 

82 

.84 

.85 

87 

.88 

90 

3.1 

.79 

.81 

.82 

.84 

.85 

.87 

.88 

.90 

.91 

.93 

3.2 

.82 

.83 

.85 

.86 

.88 

.90 

.91 

.93 

.94 

.96 

3.3 

.84 

.86 

.87 

.89 

.91 

.92 

.94 

.96 

.97 

.99 

3.4 

.87 

.88 

.90 

.92 

.93 

.95 

.97 

.99 

1.00 

1.02 

3.5 

.89 

.91 

.93 

.94 

.96 

.98 

.00 

.01 

1.03 

1.05 

3.6 

.92 

.94 

.95 

.97 

.99 

1.00 

.03 

.04 

1.06 

1.08 

3.7 

.94 

.96 

.98 

.00 

1.02 

.03 

.05 

.07 

1.09 

1.11 

3.8 

.07 

.99 

1.01 

.03 

1.04 

.06 

.08 

.10 

1.12 

1.14 

3.9 

.99 

1.01 

1.03 

.05 

1.07 

.09 

.11 

.13 

1.15 

1.17 

.0 

1.02 

1.04 

1.06 

.08 

1.10 

.12 

.14 

.16 

1.18 

1.20 

4.1 

1.05 

1.07 

1.09 

.11 

1.13 

.15 

.17 

.19 

1.21 

1.23 

.2 

.07 

1.09 

1.11 

.13 

1.15 

.18 

.20 

.22 

1.24 

1.26 

.3 

.10 

1.12 

1.14 

.16 

1.18 

.20 

.23 

.25 

1.27 

1.29 

.4 

.12 

1.14 

1.17 

.19 

1.21 

.23 

.25 

.28 

1.30 

1.32 

.5 

.15 

1.17 

.19 

.21 

1.24 

.26 

.28 

.30 

1.33 

1.35 

.6 

.17 

1.20 

.22 

.24 

1.26 

.29 

.31 

.33 

1.36 

1.38 

4.7 

.20 

1.22 

.25 

.27 

1.29 

.32 

.34 

1.36 

1.39 

1.41 

4.8 

.22 

1.25 

.27 

.30 

1.32 

.34 

.37 

1.39 

1.42 

1.44 

4.9 

.25 

1.27 

.30 

.32 

1.35 

1.37 

.40 

1.42 

1.45 

1.47 

5.0 

.27 

1.30 

.32 

.35 

1.37 

1.40 

1.42 

1.45 

1.47 

1.50 

5.1 

.30 

1.33 

.35 

.38 

1.40 

1.43 

1.45 

1.48 

1.50 

1.53 

5.2 

.33 

1.35 

.37 

.40 

1.43 

1.46 

1.48 

1.51 

1.53 

1.56 

5.3 

.35 

1.38 

.40 

.43 

1.46 

1.48 

1.51 

1.54 

1.56 

1.59 

5.4 

1.38 

1.40 

.43 

.46 

1.48 

1.51 

1.54 

1.57 

1.59 

1.62 

5.5 

1.40 

1.43 

.46 

.48 

.51 

.54 

1.57 

1.60 

1.62 

1.65 

5.6 

1.43 

1.46 

.48 

.51 

.54 

.57 

1.60 

1.62 

1.65 

1.68 

5.7 

1.45 

1.48 

.51 

.54 

.57 

.60 

i.62 

1.65 

1.68 

1.71 

5.8 

1.48 

1.51 

.54 

.57 

.59 

.62 

1.65 

1.68 

1.71 

1.74 

5.9 

1.50 

1.53 

.56 

.59 

.62 

.65 

1.68 

1.71 

1.74 

1.77 

6.0 

1.53 

1.56 

.59 

.62 

.65 

.68 

1.71 

1.74 

1.77 

1.80 

Appendix. 


279 


.Me  XI.  Butter  chart,  showing  calculated  yield  ot  buiier  <  m 
5bs.)  from  I  to  10,000  Ibs.  of  milk,  testing  3.0  to  5.3  per 
cent.  (See  directions  for  use,  p.  26C.) 


a 

3.00 

3.10 

3.20 

3.30 

3.40 

3.50 

3.60 

3.70 

3.80 

3.90 

4.00 

4.10 

f 

Milk, 

Milk, 

Ibs. 

Ibs. 

10,000 

325 

836 

348 

860 

371 

883 

394 

406 

418 

429 

441 

452 

10,000 

9,000 

293 

302 

313 

324 

334 

345 

355 

365 

376 

386 

397 

407 

9,000 

8,000 

260 

269 

278 

288 

297 

306 

315 

325 

334 

343 

353 

362 

8,000 

7,000 

228 

235 

244 

252 

260 

268 

276 

284 

293 

300 

309 

316 

7,000 

6,000 

195 

202 

209 

216 

223 

230 

236 

244 

251 

257 

265 

271 

6,000 

5,000 

163 

168 

174 

180 

186 

192 

197 

203 

209 

215 

221 

226 

5,000 

4,000 

130 

134 

139 

144 

148 

153 

158 

162 

167 

172 

176 

181 

4,000 

3,000 

97.5 

101 

104 

108 

111 

115 

118 

122 

125 

129 

132 

136 

8,000 

2  000 

65  0 

07  f, 

69  6 

7?  0 

74  ? 

76  6 

78.8 

81.2 

83.6 

85  8 

88.2 

90.4 

2,000 

1,000 

32.5 

33.6 

34.8 

36.0 

37.1 

38.3 

39.4 

40.6 

41.8 

43.9 

44.1 

45.2 

1,000 

900 

29.3 

30.2 

31.3 

32.4 

33.4 

34.5 

35.5 

36.6 

37.6 

38.6 

39.7 

40.7 

900 

800 

26.0 

26.9 

27.8 

28.8 

29.7 

30.6 

31.5 

32.5 

33.4 

34.3 

35.3 

36.2 

800 

700 

22.8 

23.5 

24.4 

25.2 

26.0 

26.8 

27.6 

28.4 

29.3 

30.0 

30.9 

31.6 

700 

600 

19.5 

20.2 

20.9 

21.6 

22.3 

23.0 

23.6 

24.4 

25.  ] 

25.7 

26.5 

27.1 

600 

500 

16.3 

16.8 

17.4 

18.0 

18.6 

19.2 

19.7 

20.3 

20.9 

21.5 

22.1 

22.6 

500 

400 

13.0 

13.4 

13.9 

14.4 

14.8 

15.3 

15.8 

16.2 

16.7 

17.2 

17.6 

18.1 

400 

300 

9.7 

10.1 

10.4 

10.8 

11.1 

11.5 

11.8 

12.2 

12.5 

12.9 

13.2 

13.6 

300 

200 

6.5 

6.7 

6.9 

7.2 

7.4 

7.6 

7.9 

8.1 

8.3 

8.6 

8.8 

9.0 

200 

100 

3.2 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

4.1 

4.2 

4.3 

4.4 

4.5 

100 

90 

2.9 

3.0 

8.1 

3.2 

8.3 

3.4 

3.6 

3.6 

3.7 

8.8 

3.9 

4.1 

90 

80 

2.6 

2.7 

2.8 

2.9 

3.0 

3.1 

3.2 

3.8 

8.4 

8.4 

3.5 

3.6 

80 

70 

2.3 

2.8 

2.4 

2.5 

2.6 

2.7 

2.8 

2.8 

2.9 

8. 

3.1 

3.2 

70 

60 

1.9 

2.0 

2.1 

2.2 

2.2 

2.3 

2.4 

2.4 

2.5 

2. 

2.7 

2.7 

60 

50 

1.6 

1.7 

1.7 

1.8 

1.9 

1.9 

2.0 

2.0 

2.1 

2. 

2.2 

2.3 

60 

40 

1.3 

1.8 

1.4 

1.4 

1.5 

1.5 

1.6 

1.6 

1.7 

1. 

1. 

1.8 

40 

30 
20 

1.0 

1.0 

1.0 

1.1 

1.1 

1.2 
g 

1.2 
g 

1.2 
8 

1. 

1. 

1. 

1.4 
9 

80 
20 

10 

| 

ft 

4 

4 

4 

4 

4 

4 

.ft 

10 

g 

.8 

<l 

ft 

3 

.4 

4 

9 

'f 

'^ 

t 

ft 

3 

ft 

4 

8 

•in 

2 

1 

ft 

.3 

ft 

3 

7 

j 

f 

*t 

1 

2 

.2 

3 

6 

.a 

.2 

.2 

.2 

.2 

.2 

.2 

5 

.1 

.1 

.1 

.2 

.2 

.3 

, 

, 

.2 

4 

.1 

.1 

.1 

.1 

.1 

.1 

. 

. 

.1 

3 

!i 

.1 

.1 

§ 

.1 

.1 

.1 

.1 

. 

.  . 

.1 

2 

1 

T 

8.00 

8.10 

3.20 

3.30 

3.40 

3.50 

3.60 

3.70 

3.80 

3.90 

4.00 

4.10 

f 

280 


Testing  MUk  and  Its  Products. 


Table  XI.    Butter  chart  (Continued). 


1 

4.20 

4.30 

4.40 

4.50 

4.  GO 

4.70 

4.80 

4.90 

5.00 

5.10 

5.20 

">.SO 

I 

Milk 

Milk 

Ibs. 

Ibs. 

10,000 

464 

476 

487 

499 

510 

522 

534 

545 

557 

568 

580 

592 

10,000 

9,000 

418 

428 

438 

449 

459 

470 

481 

491 

501 

511 

522 

533 

9,000 

8,000 

371 

381 

390 

3;>S) 

408 

418 

427 

436 

446 

454 

464 

474 

8,000 

7,000 

325 

333 

341 

349 

357 

365 

374 

382 

390 

398 

406 

414 

7,000 

6,000 

278 

286 

292 

2i)9 

306 

313 

320 

327 

334 

341 

348 

355 

6,000 

5,000 

232 

238 

244 

250 

255 

261 

267 

273 

279 

284 

290 

296 

5,000 

4,000 

186 

190 

15)5 

200 

204 

209 

214 

218 

223 

227 

232 

237 

4,000 

3,000 

139 

143 

146 

150 

153 

157 

160 

164 

167 

170 

174 

178 

3,000 

2,000 

92.8 

)3.2 

97.4 

99.8 

102 

104 

107 

109 

111 

114 

116 

118 

2,000 

1,000 

46  4 

47  6 

48  7 

49  9 

51  0 

5fl  9, 

53  4 

54  5 

55  7 

56  8 

58  0 

~>9  2 

1,000 

900 

41.8 

42.8 

43.8 

44.9 

45.9 

47.0 

48.1 

49.1 

50.1 

51.1 

52.2 

53.3 

900 

800 

37.1 

38.1 

39.0 

39.9 

40.8 

41.8 

42.7 

43.6 

44.6 

45.4 

46.4 

47.4 

800 

700 

32.5 

33.3 

34.1 

34.9 

35.7 

36.5 

37.4 

38.2 

39.0 

39.8 

40.6 

41.4 

700 

600 

27.8 

28.6 

29.2 

29.9 

30.6 

31.3 

32.0 

32.7 

33.4 

34.1 

34.8 

35.5 

600 

500 

23.2 

23.8 

24.4 

25.0 

25.5 

26.1 

26.7 

27.3 

27.9 

28.4 

29.0 

29.6 

510 

400 

18.6 

19.0 

19.5 

20.0 

20.4 

20.9 

21.4 

21.8 

22.3 

22.7 

23.2 

23.7 

400 

300 

13.9 

14.3 

14.6 

15.0 

15.3 

15.7 

16.0 

16.4 

16.7 

17.0 

17.4 

17.8 

300 

200 

9.3 

9.5 

9.7 

10.0 

10.2 

10.4 

10.7 

10.9 

11.1 

11.4 

11.6 

11.8 

200 

100 

4.6 

4.8 

4.9 

5.0 

5.1 

5.2 

5.3 

5.5 

5.6 

5.7 

5.8 

5.9 

100 

90 

4.2 

4.3 

4.4 

4.5 

4.6 

4.7 

4.8 

4.9 

5.0 

5.1 

5.2 

5.3 

90 

80 

3.7 

3.8 

3.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5 

4.5 

4.6 

4.7 

80 

70 

3.3 

3.3 

3.4 

3.5 

3.6 

3.7 

3.7 

3.8 

3.9 

4.0 

4.1 

4.1 

70 

60 

2.8 

2.9 

2.9 

3.0 

3.1 

3.1 

3.2 

3.3 

3.3 

3.4 

3.5 

3.6 

60 

50 

2.3 

2.4 

2.4 

2.5 

2.6 

2.6 

2.7 

2.7 

2.8 

2.8 

2.9 

3.0 

50 

40 

1.9 

1.9 

2.0 

2.0 

2.0 

2.1 

2.1 

2  2 

2.2 

2.3 

2.3 

2.4 

40 

30 

1.4 

1.4 

1.5 

1.5 

1.5 

1.6 

1.6 

1^6 

1.7 

1.7 

1.7 

1.8 

30 

20 

.9 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

1  1 

1.1 

1.2 

1.2 

20 

10 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.6 

.6 

.6 

.6 

.6 

10 

9 

8 

.4 
4 

.4 
4 

.4 
4 

.5 
4 

.5 
4 

.5 
4 

.5 
4 

.5 
4 

.5 
5 

.5 
5 

.5 

5 

.5 
6 

9 

8 

7 
6 

.3 
.3 

.3 
.3 

.1 

.3 

.3 

.3 

g 

.3 

.3 

.3 

.4 
.4 

.4 
.4 

7 
6 

5 

2 

V) 

o 

^ 

3 

3 

'  tj 

0 

Q 

3 

3 

3 

5 

4 

.2 

In 
.2 

c 
»J 

f] 

»2j 

.2 

.2 

c 

.  ^ 

.2 

.2 

'.2 

'.2 

4 

g 

1 

1 

f) 

cy 

o 

2 

'  f 

0 

9 

2 

9 

2 

3 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

1 

1 

1 

i 

1 

.1 

1 

1 

i 

1 

1 

1 

1 

4.40 

1 

4.20 

4.30 

4.50 

4.60 

4.70 

4.80 

4.90 

5.  CO 

5.10 

5.20 

5.30 

1 

H 

s* 

Appendix. 


281 


Table  XII.  Overrun  table,  showing  pounds  of  butter  from 
one  hundred  Ibs.  of  milk.  (See  directions  for  use, 
par.  222.) 


Per 

cent. 

1.10 

1.11 

1.12 

1.13 

1.14 

1.15 

1.16 

1.17 

1.18 

1.19 

1.20 

Per 

cent. 

fat. 

fat. 

3.0 

3.30 

3.33 

3.36 

3.39 

3.42 

3.45 

3.48 

3.51 

3.54 

3.57 

3.60 

3.0 

3.1 

3.41 

3.44 

3.47 

3.50 

3.53 

3.57 

3.60 

3.63 

3.66 

3.68 

3.72 

3.1 

3.2 

3.52 

3.55 

3.58 

3.62 

3.65 

3.68 

3.71 

3.74 

3.78 

3.81 

3.84 

3.2 

3.3 

3.63 

3.66 

3.70 

3.73 

3.76 

3.80 

3.83 

3.86 

3.89 

3.93 

3.96 

3.3 

3.4 

3.74 

3.77 

3.81 

3.84 

3.88 

3.91 

3.94 

3.98 

4.01 

4.05 

4.08 

3.4 

3.5 

3.85 

3.89 

3.92 

3.96 

3.99 

4.03 

4.06 

4.10 

4.13 

4.17 

4.20 

3.5 

3.6 

3.96 

4.00 

4.03 

4.07 

4.10 

4.14 

4.18 

4.21 

4.25 

4.28 

4.32 

3  (> 

3.7 

4.07 

4.11 

4.14 

4.18 

4.22 

4.26 

4.29 

4.33 

4.37 

4.40 

4.44 

3.'? 

3.8 

4.18 

4.22 

4.26 

4.29 

4.33 

4.C? 

4.41 

4.45 

4.48 

4.52 

4.56 

3.8 

3.9 

4.29 

4.33 

4.37 

4.41 

4.45 

4.49 

4.52 

4.56 

4.60 

4.64 

4.68 

3.9 

4.0 

.40 

4.44 

4.48 

4.52 

4.56 

4.60 

4.64 

4.68 

4.72 

4.76 

4.80 

4.0 

4.1 

.51 

4.55 

4.59 

4.63 

4.67 

4.72 

4.76 

4.80 

4.84 

4.88 

4.92 

4.1 

4.2 

.62 

4.66 

4.70 

4.75 

4.79 

4.83 

4.87 

4.91 

4.96 

5.00 

5.04 

4.2 

4.3 

.73 

4.77 

4.82 

4.86 

4.90 

4.95 

4.99 

5.03 

5.07 

5.12 

5.16 

4.3 

4  4 

84 

4  88 

4  93 

4  97 

5  O? 

5  06 

5  10 

5  15 

5  19 

5  ?4 

5  28 

4.4 

4.5 

4.95 

5.00 

5.04 

5.09 

5.13 

6.18 

5.22 

5.27 

5.31 

5.36 

5.40 

.5 

4  6 

5  06 

5  11 

5  15 

5  ?0 

5  94 

-      OH 

5  34 

5  38 

5  43 

5  47 

5  52 

.6 

4  7 

5  17 

5  ?9 

5  26 

5  31 

5  36 

5  41 

5  45 

5  49 

5  ,55 

5  59 

5  64 

.7 

4.8 

5.28 

5.33 

5.38 

").42 

5.47 

5.52 

5.57 

5.62 

5.66 

5.71 

5.7H 

.8 

4  9 

5  39 

5  44 

5  49 

5  54 

5  59 

5  64 

5  68 

5  73 

5  78 

5  83 

5  88 

.9 

5.0 

5.50 

5  55 

5.60 

5.65 

5.70 

5.75 

5.80 

5.85 

5.90 

5.95 

6.00 

5.0 

5.1 

5.61 

5.66 

5.71 

5.76 

5.81 

5.87 

5.92 

5.97 

6.02 

6.07 

6.12 

5.1 

5.2 

5.72 

5.77 

5.82 

5.88 

5.93 

5.98 

6.03 

6.08 

6.14 

6.19 

6.24 

6.i 

5  3 

5  83 

5  88 

5  94 

5  99 

6.04 

6.10 

6  15 

6  20 

6  25 

6.31 

6.36 

5*3 

5.4 

6.94 

5.99 

6.05 

6.10 

6.16 

6.21 

6.26 

6.32 

ti.37 

6.43 

6.48 

5.4 

6.5 

6.0-5 

6.11 

6.16 

6.22 

6.27 

6.33 

6.38 

6.44 

6.49 

6.55 

6.60 

5.5 

5.6 

6.16 

6.22 

6.27 

6.33 

6.38 

6.44 

6.50 

6.55 

6.61 

6.66 

6.72 

5.6 

5.7 

6.27 

6.33 

6.38 

6.44 

6.50 

6.56 

6.61 

6.67 

6.73 

6.78 

6.84 

5.7 

5.8 

6.38 

6.44 

6.50 

8.55 

6.61 

6.67 

6.73 

6.79 

6.84 

6.90 

6.96 

5.8 

5.9 
6.0 

6.49 
6.6C 

6.55 
6.66 

6.61 
6.72 

6.67 

6.78 

6.73 
f>.84 

6.79 
6.90 

6.84 
6.96 

6.90 
7.02 

6.96 
7.08 

7.02 
7.14 

7.08 
7.20 

5.9 
6.0 

282 


Testing  Milk  and  Its  Products. 


Table  XIII.  Yield  of  Cheese  from  100  Ibs.  milk  with  2.5  to 
6  per  cent,  of  fat,  and  lacometer  readings  from  26  to  30. 

(See  par.  224) 


=s 

LACTOMETEK  DEGREES. 

<L 

p 

26 

27 

28 

29 

SO 

31 

32 

33 

34 

36 

36 

BO 

ft. 

2  5 

7.28 

7.41 

7.54 

7.67 

7.81 

7.94 

8.07 

8.20 

8  33 

8.47 

8  60 

2.5 

2  6 

7.44 

7.57 

7.70 

7.83 

7.96 

8.09 

8.22 

8.35 

8.49 

8  62 

8  76 

2.6 

2.7 

7  59 

7  72 

7.85 

7.99 

8.12 

8  25 

8  38 

8.51 

8  64 

8.77 

8  91 

2.7 

2  8 

7.74 

7.87 

8.00 

8.14 

8  27 

8  40 

8  53 

8  67 

8  80 

•8  94 

9  07 

?  8 

2.9 

7.90 

8.03 

8.16 

8.30 

8.44 

8.56 

8.69 

8.82 

8.95 

9.09 

9.22 

2.9 

3.0 

8.05 

8.18 

8.31 

8.45 

8.58 

8.71 

8.84 

8.97 

9.11 

9.24 

9.37 

3.0 

3.1 

8.21 

8.34 

8.47 

8.60 

8.74 

8.87 

9.00 

9.13 

9.26 

9.39 

9.53 

3.1 

3.2 

8.36 

8.49 

8.62 

8.75 

8.89 

9.02 

9.15 

9.28 

9.42 

9.55 

9.68 

3.2 

3.3 

8.62 

8.65 

8.78 

8.91 

9.05 

9.18 

9.31 

9.44 

9.57 

9.70 

9.84 

3.3 

3.4 

8.67 

8.80 

8.93 

9.06 

9.20 

9.33 

9.46 

9.59 

9.73 

9.86 

9.99 

3.4 

3.5 

8.82 

8.96 

9.09 

9.22 

9.35 

9.48 

9.62 

9.75 

9.88 

10.01 

10.15 

3.5 

3.6 

8.98 

9.11 

9.24 

9.37 

9.50 

9.63 

9.77 

9.90 

10.03 

10.17 

10.80 

3.6 

3.7 

9.13 

9.26 

9.39 

9.52 

9.65 

9.78 

9.92 

10.05 

10.19 

10.32 

10.46 

3.7 

3.8 

9.29 

9.42 

9.55 

9.68 

9.81 

9.94 

10.08 

10.21 

10.34 

10.48 

10.61 

3.8 

3.9 

9.44 

9.57 

9i70 

9.84 

9.97 

10.10 

10.23 

10.36 

10.60 

10.64 

10.77 

3.9 

.0 

9.60 

9.73 

9.86 

10.00 

10.13 

10.26 

10.39 

10.63 

10.66 

10.79 

10.93 

.0 

1 

9.76 

9.88 

10.02 

10.16 

10.28 

10  39 

10  54 

10  68 

10*  81 

10  94 

11  08 

1 

.2 

9.90 

10.03 

10.17 

10.30 

10.43 

10.57 

10.70 

10.84 

10.97 

11.10 

11.24 

.2 

.8 

10.06 

10.19 

10.32 

10.45 

10.58 

10.72 

10.85 

10.99 

11.12 

11.25 

11.39 

.3 

.4 

10.21 

10.34 

10.48 

10.61 

10.74 

10.87 

11.00 

11.14 

11.27 

11.41 

11.55 

.4 

.5 

10.36 

10.49 

10.63 

10.76 

10.89 

11.03 

11.16 

11.29 

11.42 

11.56 

11.70 

.5 

.6 

10.52 

10.65 

10.78 

10.92 

11.05 

11.18 

11.31 

11.45 

11.68 

11.71 

11.85 

.6 

4.7 

10.67 

10.81 

10.94 

11.07 

11.20 

11.34 

11.47 

11.60 

11.73 

11.87 

12.01 

.7 

4.8 

10.83 

10.96 

11.09 

11.22 

11.36 

11.49 

11.62 

11.76 

11.89 

12.02 

12.16 

.8 

4.9 

10.98 

11.11 

11.25 

11.38 

11.51 

11.65 

11.78 

11.91 

12.04 

12.18 

12.32 

.9 

5.0 

11.14 

11.27 

11.40 

11.64 

11.67 

11.80 

11.93 

12.07 

12.20 

12.34 

12.48 

5.0 

5^1 

11.29 

11.42 

11.55 

11.69 

11.82 

11.96 

12.09 

12.23 

12.36 

12.49 

12.63 

5.1 

5.  2 

11.45 

11  58 

11.71 

11.85 

11.98 

12.11 

12.24 

12  38 

12  62 

12  66 

12  80 

5  2 

5.3 

11  60 

11  73 

11.86 

11.99 

12.13 

12  27 

12  40 

12  53 

12  67 

12  71 

12  85 

•>  3 

5.4 

11.76 

11.89 

12.02 

12.16 

12.29 

12.42 

12.55 

12.69 

12.83 

12.97 

13.01 

5.4 

5.5 

11.91 

12.04 

12.17 

12.31 

12.44 

12.58 

12.71 

12.85 

12.99 

13.12 

13.25 

5.5 

••)  .  »i 

12.07 

12.20 

12.33 

12.47 

12.60 

12.73 

12.87 

13.00 

13.14 

13.28 

13.41 

5.6 

5.7 

12.22 

12.35 

12.48 

12.62 

12.75 

12.89 

13.02 

13.16 

13.30 

13.44 

13.57 

5.7 

5.8 

12.38 

12.61 

12.64 

12.77 

12.91 

13.05 

13.18 

13.31 

13.45 

13.59 

13.72 

5.8 

5.9 

12.53 

12.66 

12.79 

12.93 

13.06 

13.19 

13.33 

13.47 

13.60 

13.74 

13.87 

5.9 

6.0 

12.  6912.82 

12.95 

13.09 

13.22 

13.35 

13.49 

13.62 

13.75 

13.89 

14.02 

6.0 

Appendix. 


283 


Table   XIV.    Comparisons  of  Fahrenheit  and  Centigrade 
(Celsius)  thermometer  scales. 


Fahren- 
heit 

Centi- 
grade. 

Fahren- 
heit 

OnU- 
frade. 

*E?r 

Oentt- 
trade. 

+212 

+100 

+178 

+80 

+140 

+60 

211 

99.44 

178 

79.44 

139 

59.44 

210 

98.89 

174 

78.89 

188 

58.89 

209 

98.33 

178 

78.33 

137 

58.33 

208 

97.78 

172 

77.78 

136 

57.78 

207 

97.22 

171 

77.22 

136 

67.22 

208 

96.67 

170 

76.67 

134 

56.67 

205 

96.11 

169 

76.11 

133 

56.11' 

204 

95.55 

168 

75.55 

132 

55.55 

203 

95 

167 

76 

131 

65 

202 

94.44 

166 

74.44 

130 

64.44 

201 

93.89 

165 

73.89 

129 

53.89 

200 

93.33 

164 

72.33 

128 

53.33 

199 

92.78 

163 

72.78 

127 

52.78 

198 

92.22 

162 

71.22 

126 

62.22 

197 

91.67 

161 

71.67 

125 

61.67 

196 

91.11 

160 

71.11 

124 

61.11 

195 

90.55 

159 

70.55 

123 

60.55 

194 

90 

158 

70 

122 

50 

193 

89.44 

157 

69.44 

121 

49.44 

192 

88.89 

156 

68.89 

120 

48.89 

191 

88.33 

156 

68.33 

119 

48.33 

190 

87.78 

154 

67.78 

118 

47.78 

189 

87.22 

153 

67.22 

117 

47.22 

188 

86.67 

152 

66.67 

116 

46.67 

187 

86.11 

151 

66.11 

115 

46.11 

186 

85.55 

150 

65.55 

114 

45.55 

186 

86 

149 

65 

113 

46 

184 

84.44 

148 

64.44 

112 

44.44 

183 

83.89 

147 

63.89 

111 

43.89 

182 

83.33 

146 

63.33 

110 

43.33 

181 

82.78 

146 

62.78 

109 

42.78 

180 

82.22 

144 

62.22 

108 

42.22 

179 

81.67 

143 

61.67 

107 

41.67 

178 

81.11 

142 

61.11 

106 

41.11 

177 

80.55 

141 

60.55 

106 

40.65 

284  Testing  Milk  and  Its  Products. 

Table  XIV.    Comparisons  of  thermometer  scales  ( Continued. ) 


Fahren- 
heit.   , 

Centi- 
grade. 

Fahren- 
heit. 

Centi- 
grade. 

Fahren- 
heit. 

Centi- 
grade. 

+104 

+40 

+68 

+20 

+32 

+o 

103 

39.44 

67 

19.44 

31 

—0.55 

102 

38.89 

66 

18.89 

30 

1.11 

101 

38.33 

65 

18.33 

29 

1.67 

100 

37.78 

64 

17.78 

28 

2.22 

99 

37.22 

63 

17.22 

27 

2.78 

98 

36.67 

62 

16.67 

26 

3.33 

97 

36.11 

61 

16.11 

25 

3.89 

96 

35.55 

60 

15.55 

24 

4.44 

95 

35 

59 

15 

23 

5 

94 

34.44 

58 

14.44 

22 

5.55 

93 

33.89 

57 

13.89 

21 

6.11 

.       92 

33.33 

56 

13.33 

20 

6.67 

91 

32.78 

55 

12.78 

19 

7.22 

90 

32  22 

54 

12.22 

18 

7.78 

89 

31.67 

53 

11.67 

17 

8.33 

88 

31.11 

52 

11.11 

16 

8.89 

87 

30.55 

51 

10.55 

15 

9.44 

86 

30 

50 

10 

14 

10 

85 

29.44 

49 

9.44 

13 

10.55 

84 

28.89 

48 

8.89 

12 

11.11 

83 

28.33 

47 

8.33 

11 

11.67 

82 

27.78, 

46 

7.78 

10 

12.22 

81 

27.22 

45 

7.22 

9 

12.78 

80 

26.67 

44 

6.67 

8 

13.33 

79 

26.11 

43 

6.11 

7 

13.89 

78 

25.55 

42 

5.55 

6 

14.44 

77 

25 

41 

5 

5 

15.00 

76 

24.44 

40 

4.44 

4 

15.55 

75 

23.89 

39 

3.89 

3 

16.  11 

74 

23.33 

38 

3.33 

2 

16.67 

73 

22.78 

37 

2.78 

1 

17.22 

72 

22.22 

36 

2.22 

0 

17.78 

71 

21.67 

35 

1.67 

—1 

18.33 

70 

21.11 

34 

1.11 

2 

18.89 

69 

20.55 

33 

0.55 

3 

19.44 

To  convert  deg.  Fahrenheit  to  corresponding  deg.  Centigrade: 
Subtract  32,  multiply  difference  by  5,  and  divide  by  9. 
Example:    Which  degree  Centigrade  corresponds  to  110°  F.T    110-82  = 

78;  78  X  6  =  390;  390  +  9  =  43.33. 

To  convert  deg.  Centigrade"  to  corresponding  deg.  Fahrenheit: 
Multiply  by  9,  divide  product  by  5,  and  add  32  to  quotient. 

Example:    Which  degree  Fahrenheit  corresponds  to  95.50  C.?    96.5  X  •  • 
868.5;  «MJ5  *  6  =  171.8;  171.0  +  32  =  203.6. 


Appendix,  285 

Table  XV.     Comparison  of  metric  and  customary  weights  and 


measures. 


Customary 
weights  and 
measures. 

Equivalents  in 
metric  system. 

Metric  weights 
and 
measures. 

Equivalents  In 
customary  system. 

1  inch 

2  54  centimeters 

1  meter 

39  37  inches 

1  foot 

3048  meter 

1  meter 

1  0936  yards 

1  mile 

1  6094  kilometers 

kilometer 

6214  mile 

1  square  inch.. 
1  square  foot  .. 
1  square  yard. 
1  acre 

6.452  sq.  centimeters. 
9.29  sq.  decimeters. 
.836  sq.  meter. 
4047  hectare 

sq.  centimeter 
square  meter.  . 
square  meter- 
hectare 

.155  sq.  inch. 
10.  764  sq.  feet. 
I.l96sq.  yards. 
•>  471  acres 

1  cubic  inch 

16  387  cc 

cc 

061  cubic  inch 

1  cubic  foot.... 
1  cubic  vard... 
1  bushel 

.0283  cub.  meter. 
.7<>o  cub.  meter 
355°  hectolitei 

cub.decimeter 
cub.  meter  
hectoliter 

til.  023  cubic  inchea 
35.314  cub.  feet. 
%)  8377  bushels. 

1  fluid  ounce 

29  57  cc 

cc 

0338  fluid  ounce. 

1  quart 

9464  liter 

liter 

1  0567  quarts. 

1  gallon  
1  grain  
1  ounce  (av.)-. 
1  pound  (av.  ) 

3.7854  liters. 
64.8  milligrams. 
28.  35  gnu  as. 
.4536  kilogram. 

decaliter  
gram.  
grain  
kilogram  

2.'>417  <  marts. 
15.43  gniins. 
.035274  ounce. 
2.2046|>ounds(av. 

Table  XVI.     Specific  Gravity  and  Weight  of  one  Gallon  of 
Cream,  in  Pounds,  arranged  according  to  the  per  cent,  of  fat. 


Per  cent 
of  fat 
in  cream 

Specific 
gravity 
of  cream 

Weight  of 
one  gallon 
Ibs. 

Per  cent 
of  fat 
in  cream 

Specific 
gravity 
of  cream 

Weight  of 
one'tgallon 
Ibs. 

0 

1.036 

8.6391 

35 

0.9963 

8.3076 

10 

.0243 

8.5417 

36 

0.9952 

8.2985 

15 

.0186 

8.4938 

37 

0.9941 

8.2894 

16 

.0174 

8.4843 

38 

0.9930 

8.2804 

17 

.0163 

8.4749 

39 

0.9919 

8.2714 

18 

.0152 

8.4654 

40 

0.9908 

8.2621 

19 

.0140 

8.4560 

41 

0.9897 

8.2534 

20 

.0129 

8.4465 

42 

0.9886 

8.2444 

21 

.0118 

8.4372 

43 

0.9875 

8.2354 

22 

.0107 

8.4278 

44 

0.9864 

8.2265 

23 

.0096 

8.4184 

45 

0.9854 

8.2176 

24 

.0085 

8.4090 

46 

0.9843 

8.2087 

25 

.0073 

8.3997 

47 

0.9832 

8.1998 

26 

.0062 

8.3905 

48 

0.9821 

8.1909 

27 

.0051 

8.3812 

49 

0.9811 

8.1821 

28 

.0040 

8.3719 

50 

0.9801 

8.1733 

29 

.0029 

8.3626 

51 

0.9790 

8  .  1646 

30 

.0017 

8.3534 

52 

0.9780 

8.1558 

31 

1.0006 

8.3443 

53 

0.9770 

8.1470 

32 

0.9995 

8.3352 

54 

0.9760 

8.1382 

33 

0.9984 

8.3260 

55 

0.9749 

8.1294 

34 

0.9973 

8.3168 

286  Testing  Milk  and  Its  Products. 

SLGGLSIIO\S  regarding    the  organization  of  co-operativ« 
creameries    and  cheese   factories. 

When  the  farmers  of  a  neighborhood  are  considering  the 
establishment  of  a  creamery  or  cheese  factory,  they  should  first 
of  all  make  an  accurate  canvas  of  the  locality  to  ascertain  the 
number  of  cows  that  can  be  depended  on  to  supply  the  factory 
with  milk.  The  area  which  may  be  drawn  from  will  vary 
according  to  the  kind  of  factory  which  it  is  desired  to  operate. 
A  successful  separator  creamery  will  need  at  least  400  cows 
within  a  nidi  us  of  four  to  five  miles  from  the  proposed  factory.1 
Small  cheese  factories  can  be  operated  with  less  milk,  and 
gat  he  red -cream  and  butter  factories  generally  cover  a  much 
larger  territory  than  that  mentioned.  In  all  cases,  however, 
the  question  of  the  number  of  cows  contributing  to  the  enter- 
prise must  be  fully  settled  before  further  steps  are  taken,  since 
this  is  a  point  upon  which  success  will  largely  depend. 

Methods  of  organization.  The  farmers  should  form  their  own 
organization,  and  not  accept  articles  of  agreement  proposed  by 
traveling  agents.  An  agreement  to  supply  milk  from  u  stated 
number  of  cows  should  be  signed  by  all  expecting  to  join  the 
association.  When  a  sufficient  number  of  cows  has  been 
pledged  to  insure  the  successful  operation  of  a  factory,  the  farm- 
ers agreeing  to  supply  milk  should  meet  and  form  an  organi- 
zation. This  may  be  done  according  to  either  of  the  following 
plans  which  have  been  known  to  give  good  satisfaction. 

Raising  money  for  building  and  equipment. 

First. — Each  member  will  sign  an  agreement  to  pay  on  or 
before  a  given  date  for  a  certain  number  of  shares  in  the  com- 
pany at dollars  per  share;  or, 

Second. — An  elected  board  of  directors  may  be  authorized  to 

borrow  a  sum  of  money  not  exceeding thousand  dollars 

on  their  individual  responsibility,  and  the  sum  of cento, 

(usually  five  cents)  per  hundred  pounds  of  milk  received  at 
the  factory  shall  be  reserved  for  the  payment  of  this  borrowed, 
money. 

1  Bull.  64,  Wisconsin  experiment  station. 


Appendix.  287 

Constitution  and  by-laws  of  a  co-operative  association  are  drawn 
up  and  signed  by  the  prospective  members  of  the  association 
when  it  has  been  determined  to  form  such  an  association.  It 
is  impossible  to  include  in  an  illustration  all  the  articles  and 
rules  that  may  be  found  useful  in  each  particular  instance;  the 
following  suggestions  in  regard  to  some  of  the  points  to  be  in- 
cluded in  the  documents  are  given  as  a  guide  only.  It  may  be 
found  advisable  to  modify  them  in  various  ways  to  meet  the 
needs  of  the  organization  to  be  formed. 

After  the  constitution  and  by-laws  have  been  drawn  up  and 
made  plain  to  all  the  members  of  the  association,  they  should 
be  printed  and  copies  distributed  to  all  parties  Interested. 

CONSTITUTION 

OR 
ARTICLES   OP   AGREEMENT   OF   THE ASSOCIATION.' 

1.  The  undersigned,  residents  within  the  Counties  of , 

State  of ,  herebyagree  to  become  members  of  the 

Co-operative  Association,   which  is  formed  for  the  purpose  of 
manufacturing  butter  or  cheese  from  whole  milk. 

2.  The  regular  meetings  of  the  association  shall  be  held  an- 
nually on  the day  of  the  month  of. Special 

meetings  may  be  called  by  the  president,  or  on  written  request 
of  one-third  of  the  members  of  the  association,  provided  three 
day's  notice  of  such  meeting  is  sent  to  all  members. 

Meetings  of  the  board  of  directors  may  be  called  in  the  same 
way,  either  by  the  president  or  by  any  two  members  of  the 
board  of  directors. 

3.  Ten  members  of  the  association,  or  three  of  the  board  of 
directors,  shall  constitute  a  quorum  for  the  transaction  of  busi- 
ness. 

4.  The  officers  of  the  association  shall  include  president,  sec- 
retary, treasurer,  one  of  whom  is  also  elected  manager,  and 
these  officers  together  with  three  other  members  of  the  associa- 


JThe  following  publications  have  been  freely  used  in  preparing  this 
constitution  and  by-laws;  Woll,  Handbook  f.  Farmers  and  Dairymen: 
Minn,  experiment  station,  bull.  No.  35;  Ontario  Agricultural  College, 
special  bulletin,  May  1897.  See  also  Iowa  exp.  station,  bull.  No.  139. 


288  Testing  Milk  and  Its  Products. 

tion  shall  constitute  the  board  of  directors.  Each  of  these  six 
officers  shall  be  elected  at  the  annual  meeting  and  hold  office 
for  one  year,  or  until  their  successors  have  been  elected  and 
qualified.  Any  vacancies  in  the  board  of  directors  may  be  filled 
by  the  directors  until  the  next  annual  meeting  of  the  association. 

5.  The  duties  of  the  president  shall  be  to  preside  at  all  meet- 
ings of  the  association,  and  perform  the  usual  duties  of  such 
presiding  officers.    He  shall  sign  all  drafts  and  documents  of 
any  kind  relating  to  the  business  of  the  association,  and  pay 
all  money  which  comes  into  his  possession  by  virtue  of  his 
office,  to  the  treasurer,  taking  his  receipt  therefor.    He  shall 
call  special  meetings  of  the  association  when  deemed  necessary. 

In  the  absence  of  the  president,  one  of  the  board  of  directors 
•hall  temporarily  fill  the  position. 

6.  The  secretary  shall  attend  all  business  meetings  of  the 
association  and  of  the  board  of  directors  and  shall  keep  a  care- 
ful record  of  the  minutes  of  the  meetings.    He  shall  also  give 
notices  of  all  meetings  and  all  appointments  on  committees, 
etc.    He  shall  sign  all  papers  issued,  conduct  the  correspond- 
ence and  general  business  of  the  association,  and  keep  a  correct 
financial  account  between  the  association  and  its  members.    He 
shall  have  charge  of  all  property  of  the  association  not  other- 
wise disposed  of,  give  bonds  for  the  faithful  performance  of  his 
duties,  and  receive  such  compensation  for  his  services  as  the 
board  of  directors  may  determine. 

7.  The  treasurer  shall  receive  and  give  receipt  for  all  money 
belonging  to  the  association,  and  pay  out  the  same  upon  orders 
signed  by  the  president  and  the  secretary.    He  shall  give  such 
bonds  as  the  board  of  directors  may  require. 

8.  The  board  of  directors  shall  audit  the  accounts  of  the 
association,  invest  its  funds,  appoint  agents,  and  determine  all 
compensations.    They  shall  prescribe  and  enforce  the  rules  and 
regulations  of  the  factory.    They  shall  cause  to  be  kept  a  rec- 
ord of  the  weights  and  testa  of  the  milk  or  cream  received  from 
each  patron,  «<ie  products  sold,  the  running  expenses,  etc.,  and 
si  all  divide  among  the  patrons  the  money  due  them  each 
month.    They  shall  also  make  some  provision   for  the  with- 


Appendix.  :>89 

drawal  of  any  member  from  the  association,  and  make  a  re- 
port in  detail  to  the  association  at  the  annual  meeting.  Such 
report  shall  include  the  gross  amount  of  milk  handled  during 
the  year,  the  receipts  from  products  sold,  and  all  other  re- 
ceipts, the  amounts  paid  for  milk  and  for  running  expenses, 
and  a  complete  statement  of  all  other  matters  pertaining  to 
the  business  of  the  association. 

9.  Among  the  rules  and  regulations  to  be  enforced  by  the 
board  of  directors  may  be  included  some  or  all  of  the  follow- 
ing: 

a.  Patrons  shall  furnish  all  the  milk  from  the  cows  prom- 
ised at  organization  of  the  association. 

b.  Only  sweet  and  pure  milk  will  be  accepted  at  the  fac- 
tory, and  any  tainted  or  sour  milk  shall  be  refused. 

c.  The  milk  of  each  patron  shall  be  tested  at  least  three 
times  a  month. 

d.  Any  patron  proved  to  be  guilty  of  watering,  skimming 
or  otherwise  adulterating  the  milk  sent  to  the  factory,  or  by 
taking  more  than  80  pounds  of  skim  milk  or  whey  for  every 
100  pounds  of  whole  milk  delivered  to  the  factory,  shall  be 
fined  as  agreed  by  the  association. 

e.  A  patron's  premises  may  be  inspected  at  any  time  by 
the  board  of  directors,  or  their  authorized  agent,  for  the  pur- 
pose of  suggesting  improvements  in  the  methods  of  caring 
for  the  milk  or  the  cows,  in  drainage  and  general  cleanli- 
ness; or  to  secure  samples  of  the  milk  of  his  cows  for  ex- 
amination when  it  is  deemed  necessary. 

10.  Any  changes  or  amendments  to  the  by-laws  or  consti- 
tution of  the  association  must  be  made  in  writing  by  the 
parties  proposing  the  same,  and  posted  prominently  in  a  con- 
spicuous place  at  the  creamery,  at  least  two  weeks  previous 
to  their  being  acted  upon.    Such  changes  to  be  in  force  must 
be  adopted  by  a  two-thirds  vote  of  the  stockholders. 

11.  In  voting  at  any  annual  or  special  meeting  of  the  asso- 
ciation, the  members  shall  be  entitled  to  one  vote  for  each  cow 
supplying  the  milk  to  the  factory,  or  for  each  share  of  the 
stock  owned  by  them,  as  agreed  upon. 


INDEX 


The  figures  refer  to  pages  in  the  book. 


Acid  bottle,  Swedish,  47. 

Acid   measures,   31,  47,   54. 

Acid  tester,  Swedish,  67. 

Acidimeter,  Devarda's,  124. 

Acidity  of  cream,  125,  129;  esti- 
mation of,  135. 

Acidity  of  milk,  cause  of,  119 ;  de- 
termination of,  132  ;  methods  of 
testing,  120. 

Acidity  pellets,  125. 

Adulteration  of  milk,  111,  115, 
244 ;  calculation  of,  115. 

Adulterated  butter,  240,  242; 
cheese,  245. 

Albumen,  14 ;  determination  of,  In 
milk,  225. 

Albuminoids,  13. 

Alcohol  test,  135. 

Albumose,  14. 

Alkaline  tablet  test,  124;  stand- 
ard solution  of,  126 ;  accuracy, 
128. 

Alkaline  tabs,  136. 

American  cheddar  cheese,  21. 

Ames  method  for  determining 
water  in  butter,  236. 

Amphoteric  reaction  of  milk,  119. 

Amyl  alcohol,  use  in  cream  test- 
ing, 88. 

Analysis,  chemical,  of  butter,  231 ; 
butter  milk,  228;  cheese,  243; 
condensed  milk,  229 ;  cream, 
228  ;  milk,  217  ;  skim  milk,  228  ; 
whey,  228. 

Appendix,  259. 

Artificial  butter,  detection  of,  240. 

Ash,  determination  of,  in  butter, 
232;  in  cheese,  245;  in  milk, 
227. 


Babcock  glassware,  standard,  spe- 
cifications for,  258. 

Babcock  test,  the,  4,  28;  Bart- 
letts  modification,  71;  direct- 
tions  for,  29 ;  discussion  of  de- 
tails, 37  ;  for  butter,  96 ;  for 
butter  milk,  94  ;  for  cheese,  97  ; 
for  condensed  milk,  98;  for 
cream,  75,  180 ;  for  ice-cream, 
100;  for  skim  milk,  90;  for 
whey,  94 ;  glassware  used  In, 
37,  258a;  modifications  of,  71; 
scales  for  weighing  cream,  chesee, 
etc. ,80,233  ;water  to  be  used  in,68. 

Babcock  testers,  54  ;  electrical,  63  ; 
hand  testers,  60  ;  power  testers, 
61 ;  steam  turbine,  61. 

Bartlett's  modification  of  Babcock 
test,  48,  71. 

Bausch  and  Lomb  centrifuge,  71. 

Beimling  test,  5. 

Benkendorf  moisture  test,  239. 

Bi-carbonate  of  soda,  detection  of, 
251. 

Bi-chromate  of  potash,  108,  168; 
solution  of,  108. 

Blended  milk,  254. 

Board  of  health  degrees,  106. 

Boiled  milk,  detection  of,  249. 

Boiling  test,  the,  242. 

Boracic  acid  in  dairy  products, 
136.  252. 

Borax  in  dairy  products,  252. 

Butter,  artificial,  12 ;  detection  of, 
240. 

Butter  chart,  279:  use  of,  197. 

Butter,  20  ;  Babcock  test  for,  196 ; 
chemical  analysis  of,  231 ;  com- 
plete analysis  in  same  sample. 


292 


Testing  Milk  and  Its  Products. 


232;  composition  of,  21,  259: 
creamery  methods  of  estimating 
water  in,  233;  definition,  257; 
determination  of  ash,  232  ;  case- 
In,  231 ;  fat,  231 ;  salt,  233,  239  ; 
water,  231 ;  rapid  estimation  of 
water  233;  Ames  method,  236; 
Benkendorf  moisture  tester,  239: 
Cornell  test,  237  ;  Dean's  meth- 
od, 237;  Cray's  method,  235; 
Irish  test,  236;  Mitchell-Walker 
test,  235;  Patrick's  method, 
235;  Wisconsin  high-pressure 
oven  method,  237;  processs,  255; 
renovated,  255 ;  sampling  for 
analysis,  95,  231 ;  scales  for 
weighing,  81,  233;  standard, 
257.  variations  in  composition, 
188;  yield,  calculation  of,  187. 

Butter  fat,  amount  due,  at  12-25 
cents  per  lb.,  272 ;  conversion 
factor  for,  196  ;  definition,  255  ; 
determination  of  specific  grav- 
ity, 240;  volatile  fatty  acids, 
241  ;  expansion  coefficient,  36 ; 
specific  gravity,  38 ;  determin- 
ation, 241;  standard,  257;  test 
and  yield  of  butter,  187. 

Butter  making,  quantities  of  prod- 
ucts obtained  in,  21. 

Butter  milk,  21 ;  Babcock  test  for, 
94;  chemical  analysis  of,  228; 
composition,  259;  definition 
256;  specific  gravity,  229. 

Calculation  of  adulteration  of 
milk,  115;  of  concentration  of 
condensed  milk,  230;  of  milk 
solids,  109  ;  of  overrun,  195  ;  of 
sp.  gr.  of  milk  solids,  113  ;  of 
yield  of  butter,  187,  196,  197; 
of  cheese,  199 ;  of  dividends  at 
creameries,  203  ;  at  cheese  fac- 
tories, 213  ;  of  percentages,  172. 

Calibration  of  glassware,  48 ; 
Trowbridge  method,  51. 

Carbohydrates,  15. 

Casein,  13 ;  determination  of,  in 
butter,  231  ;  in  cheese,  243 ;  in 


milk,  3,  226 ;  Hart's  method, 
226. 

Centrifugal  machines,  54. 

Chamber-land  filters,  14. 

Cheddar  cheese,  American,  21 ; 
composition,  258. 

Cheese,  21 ;  Babcock  test  for,  97  ; 
calculating  yield  of,  from  casein 
and  fat,  201;  from  fat,  199; 
from  solids  not  fat  and  fat,  200  ; 
composition,  21,  259;  chemical 
analysis  of,  243 ;  definitions, 
257;  determination  oi  ash.  245; 
casein,  243;  fat,  243;  water, 
243  ;  "filled,"  detection  of,  244  ; 
quality  of,  from  milk  of  differ- 
ent richness,  211 ;  sampling,  97  ; 
standard,  256  ;  yield,  calculation 
of,  199;  yield  of,  from  milk 
with  2.5  to  6  per  cent,  fat  and 
lactometer  readings  from  26  to 
36,  281 ;  yield  of,  and  quality  ef 
milk,  relation  between,  200. 

Cheese  factories,  calculating  divi- 
dends at,  213  ;  co-operative,  216, 
285;  proprietary,  215. 

Cholesterin  in  milk,  18. 

Citric  acid  in  milk,  18. 

Cleaning  solution  for  test  bottles, 
43. 

Cleaning  test  bottles,  40 ;  appa- 
ratus for,  41,  44. 

Cochran's  test,  5. 

Coloring  matter  in  milk,  detection 
of,  247. 

Colostrum  milk,  18 ;  composition 
of,  258. 

Combined  acid  bottle,  47. 

Composite  samples,  151;  care  of, 
170;  case  for  holding,  166; 
methods  of  taking,  160 ;  pre- 
servatives for,  167. 

Composite  sampling,  accuracy  of, 
167 ;  use  of  drip  sample,  162 ; 
McKay  sampler,  165;  Michels' 
cream  sampling  tube,  165  ;  one- 
third  sample  pipette,  166 ;  Sco- 
vell  sampling  tube,  163  ;  tin  dip- 
per, 160. 


Index. 


293 


Composition  of  butter,  259;  but- 
ter milk,  259;  cheese,  259;  col- 
ostrum milk,  259;  condened 
milk,  259;  cream,  259,  milk,  18; 
259;  milk  ash,  17;  skim  milk, 
259;  whey,  259. 

Condensed  milk,  22  ;  analysis  of, 
229;  composition  of,  259;  de- 
termination of  concentration, 
230 ;  of  sp.  gr.  of,  230 ;  testing 
of,  98. 

Control  samples  of  milk,  111. 

Conversion  factor  for  butter  fat, 
196. 

Conversion  tables  for  thermome- 
ter scales,  282 ;  for  weights  and 
measures,  284. 

Cornell  test  for  determining  water 
in  butter,  237. 

Cows,  number  of  tests  required  in 
testing,  147 ;  single,  sampling 
milk  of,  150 ;  when  to  test,  149. 

Cream,  19,  228;  acidity  of,  125, 
129 ;  Babcock  test  for,  75,  180 ; 
bottles,  79;  care  In  sampling, 
necessity  of,  182  ;  clotted,  255  ; 
definition,  257;  determination  of 
acidity  of,  125,  135  ;  errors  of 
measuring  in  testing,  76 ;  evap- 
orated, 257;  fat  in  1  to  1000 
Ibs.,  testing  12  to  50  per  cent., 
271;  gelatin  in,  detection  of 
249  ;  overrun,  194  ;  pasteurized, 
detection  of,  248 ;  scales,  80 ; 
separator,  19 ;  gathering  and 
sampling,  185 ;  separation  of, 
influence  of  temperature,  185 ; 
sour,  determination  of  acidity, 
125  ;  spaces,  176  ;  specific  grav- 
ity, 77,  102;  standard,  257; 
starch  in,  250 ;  testing,  75 ; 
eliminating  meniscus  in,  87 ; 
testing  outfit,  181  ;  testing  at 
creameries,  176;  tests,  correct 
readings  of,  85,  87 ;  use  of  5  cc. 
pipette  in  sampling,  86 ;  use  of 
milk  test  bottles,  84;  test  bot- 
tles, 79  ;  weight  of,  delivered  by 


17.6  cc.  pipette,  77 ;  weight  of 
1  gal..  285. 

Creameries,  calculating  dividends 
at,  203;  co-operative.  205.  285; 
cream  testing  at,  176 ;  proprie- 
tary, 204. 

Creamery  inch,  1,  177. 

Curd  test,  the  Wisconsin  improved, 
137. 

Dean's  method  for  determining 
water  in  butter,  237. 

Definitions  of  milk  and  its  prod- 
ucts, 255. 

DeLaval's  butyrometer,  8. 

Devarda's  acidimeter,  124. 

Diameter  of  tester  and  speed  re- 
quired, relation  between,  57. 

Dividends,  calculating  at  cheese 
factories,  215 ;  at  creameries, 
205 ;  of  both  milk  and  cream  at 
the  same  factory,  211. 

Dividers,  use  of,  37. 

Double-necked  test  bottles,  92 ; 
value  of  divisions  of,  93. 

Draining-rack  for  test  bottles,  42. 

Eichler's  Saurepillen,  125. 
Expansion. coefficient  of  butter  fat. 


Failyer  and  Willard's  test,  4. 

Farrington's  alkaline  tablet  test, 
124. 

Fat,  11 ;  color  of,  an  Index  to 
strength  of  acid  used,  67 ;  con- 
tent, causes  of  variation  In,  146  ; 
determination  of,  in  butter,  231 ; 
In  cheese,  244;  in  milk,  221; 
globules,  11 ;  Gottlieb's  method 
for  determining,  222 ;  influence 
of  temperature  on  separation  of, 
69 ;  measuring  of,  in  cream  test- 
ing, 86;  in  milk  testing,  35; 
pounds  in  1-10,000  Ibs.  of  milk, 
testing,  3  to  5.35  per  cent.,  266 ; 
speed  required  for  complete  sep- 
aration of,  59. 


294 


Testing  Milk  and  Its  Products. 


Fat-saturated      alcohol,      use      in 

cream  testing,  88. 
Fermentation  test,  the,  139. 
Filled  cheese,  detection  of,  245. 
"Fitch's  Salt  Analysis,"  239. 
Fjord's  centrifugal  cream  test,  8. 
Flourids.  detection  of,  253. 
Food,   influence  of  on   quality   of 

milk,  144,  146,  150. 
Food  stannas,  Government,  255. 
Fool  pipettes,  46. 
Formaldehyne,  detection  of  253. 
Frozen  milk,  sampling  of,  27. 

Gauges  of  cream,  176. 

Gelatine  in  cream,  detection  of, 
249. 

Gerber's  acid-butyrometer,  7 ;  fer- 
mentation test,  139. 

Glassware  used  in  the  Babcock 
test,  37  ;  calibration  of,  48. 

Globulin,  15. 

Glycerids  of  fatty  acids,  13. 

Glymol,  use  in  cream  testing,  88. 

Goat  cheese,  14. 

Gottlieb  method,  the,  222. 

Government  food  standards,  255. 

Gray's  test  for  water  in  butter, 
235. 

Grain-feeding,  heavy,  influence  of, 
on  quality  of  milk,  155. 

Hand  separator  cream,  gathering 

and  sampling,  185. 
Hand  testers,  00. 
Hart's    test    for    casein    in    milk, 

226. 

Hemi-albumose,  14. 
Herd    milk,    variations    in,    153 ; 

ranges  in  variations  of,  154. 
Hydrostatic  balance,  82. 
Hypoxanthin,   18. 

Ice-cream,  test  of,  100  ;  definitions, 
257:  apparatus  for  determin- 
ing overrun,  101. 

Immersion  refractometer,  use  of 
for  detection  of  watered  milk, 
245. 


Introduction,  1. 

Iowa  station  test,  5. 

Irish  test  for  water  in  butter,  236. 

Kumiss,  258. 

Lactic  acid  in  milk,  16. 

Lactocrite,  5,  7. 

Lactose,  15. 

Lactochrome,  18. 

Lactometer,  the,  and  its  applica 
tion,  102  ;  bi-chromate,  influence 
on,  108 ;  cleaning  of,  108 ;  de- 
grees, 101 ;  N.  Y.  board  of 
health,  106,  261 ;  Quevenne, 
103 ;  reading  the,  106 ;  testing 
accuracy  of,  108 ;  time  of  tak- 
ing readings,  107. 

Lecithin  in  milk,  18. 

Leffmann  and  Beam  test,  5. 

Legal  standards  for  milk,  112,  260; 
for  dairy  products,  260. 

Liebermann's  method,  5. 

Macroscopic  impurities  in  milk, 
250. 

Manns'  test,  121;  testing  outfit, 
124. 

Marschall  acid  test,  131 ;  rennet 
test,  141. 

McKay  sampling  tube,  165. 

Measuring  fa^  column  in  testing 
cream,  86,  87 ;  in  testing  milk, 
35. 

Mercury,  calibration  with,  51 ; 
cleaning,  52. 

Metric  and  customary  systems  of 
weights  and  measures,  compar- 
ison of,  284. 

Michels'  cream  sampling  tube,  165. 

Milk,  acidity  of,  119,  132  ;  albu- 
men in,  12 ;  adulteration  of, 
111 ;  amphoteric  reaction  of, 
119;  ash,  composition  of,  17; 
blended,  definition,  255;  boiled, 
detection  of,  249 ;  casein  in, 
13 ;  chemical  analysis  of,  217  ; 
cholesterln  In,  18 ;  churned, 
sampling  of,  24  ;  citric  acid  in, 
18;  colostrum,  18;  composition 


Index. 


295 


of  |[10,  18,  259;  composite 
sampling  of,  160  ;  condensed,  22, 
98,  259;  correction  table  for 
specific  gravity,  262;  defini- 
tions, 254  ;  detection  of  coloring 
matter,  247;  of  preservatives, 
135,  252;  determination  of  acid- 
ity, 132  ;  of  ash,  227  ;  of  casein 
and  albumen,  223 ;  of  fat,  221 ; 
of  milk  sugar,  226;  of  solids, 
221 ;  of  specific  gravity,  217 ; 
of  water,  220 ;  fat  In,  11;  from 
cows  in  heat,  112;  from  sick 
cows,  112 ;  from  single  cows, 
sampling  of,  150 ;  variations  In, 
142 ;  frozen,  sampling  of,  27 ; 
gases,  18  ;  hypoxanthin,  18  ;  lac- 
tochrome,  18;  lactose,  15;  leci- 
thin, 18;  legal  standards,  112, 
260;  macroscopic  impurities, 
251;  nrneral  components,  16; 
partially  churned,  sampling  of, 
24  ;  pasteurized,  detection,  248  ; 
preservatives,  detection,  130, 
252;  quality  of.  influence  of  food, 
155 ;  of  heavy  grain  feeding, 
155  ;  of  pasture,  156  ;  method  of 
improving,  158 ;  sampling,  23, 
29;  scale,  Richmond's,  110; 
scales,  150;  serum,  10;  skim- 
ming, 116;  solids,  10;  calcula- 
tion of,  109  ;  specific  gravity  of, 
113  ;  souring  of,  15  ;  sour,  sam- 
pling of,  26 ;  standards,  112, 
254  ;  sugar,  15 ;  tests  for  adul- 
teration :  nitric  acid  test,  245  ; 
sp.  gr.  of  skim  milk,  milk  serum, 
or  whey,  247;  testing  on  the 
farm,  142;  testing  purity  of, 
137  ;  urea,  18  ;  water,  11 ;  water- 
ing of,  116 ;  detection  of,  by  re- 
fractometer,  245  ;  watering  and 
skimming,  117. 

Milk  test,  a  practical,  need  of,  1 ;  \ 
requirements  of,   6 ;  bottle,  use 
of,   in  testing  cream,  84  . 

Milk  tests,  Babcock,  4,  6;   Beim- 
ling   (Leffmnnn  and   Beam),  5; 


Cochran,  5 ;  DeLaval  butyrome- 
ter,  8 ;  Failyer  and  Wlllard,  4 ; 
Fjord,  8 ;  foreign,  7 ;  Gerber 
acid-butyrometer,  7 ;  introduc- 
tion of,  4  ;  lactocrite,  5,  7 ;  Lle- 
bcrmann,  5 ;  Llndstrom,  9 ; 
Nahm,  5 ;  Parson,  4 ;  Patrick 
(Iowa  station  test),  5;  RSse- 
Gottlieb,  5,  222  ;  sal-method,  5  ; 
Schmied,  5 ;  Short,  4 ;  sin-acid, 
7  ;  Thorner,  5  ;  Wollny  rcfracto- 
meter,  9. 

Milk  products,  composition  of,  19, 
259. 

Milk  testing,  28 ;  on  the  farm,  142. 

Mitchell-Walker  test,  235. 

Mojonnier  test,  99. 

Monrad  rennet  test,  the,  140. 

Nahm's  test.  5. 

N.  Y.  board  of  health  lactometer, 

105 ;    degrees    corresponding    to 

Quevenne     lactometer     degrees, 

261. 
Nitric  acid  test  for  adulteration  of 

milk,  246. 

Non-fatty  milk  solids,  10. 
Normal  solutions,  121. 
Nuclein,  14. 

Official  tests  of  cows,  150. 

Oil-test  churn,  2,  177. 

Oleomargarine,  detection  of,  :MO, 
242 ;  cheese,  detection  of,  245 ; 
tests  for  artificial  coloring  mat- 
ter in,  243. 

One-third  sampling  pipette,  use  of, 
166. 

Organization  of  co-operative  cream- 
eries and  cheese  factories,  sug- 
gestions concerning,  285. 

Overrun.  190  ;  calculation  of,  195  ; 
factors  influencing,  190 ;  table, 
199,  280 ;  from  cream,  194 ; 
from  milk,  190. 

Parsons'  test,  5. 

Pasteurized  milk  or  cream,  detec- 
tion of,  248. 


296 


Testing  Milk  and  Its  Products. 


Pasture,  influence  on  quality  of 
milk,  156. 

Patrick's  test,  5  ;  method  for  de- 
termining water  in  butter.  235. 

Percentages,  average,  methods  of 
calculation,  172  ;  fallacy  of  aver- 
aging, 171. 

Phenolphtalein.  122. 

Physician's  centrifuge,  use  of,  in 
milk  testing,  72. 

Pipettes,  30.  45;  proper  construc- 
tion of  points,  45  ;  proper  meth- 
od of  emptying,  31 ;  calibration, 
54. 

Pooling  system,  3. 

Potassium  bi-chromate,  168. 

Power  testers.  61. 

Preservaline,  135,  252;  detection  of 
in  milk,  135,  252. 

Preservatives,  for  composite  sam- 
ples, 167 ;  in  milk,  detection  of, 
135,  252. 

Primost,  14. 

Process  butter,  detection  of,  242. 

Proteose,  14. 

Quevenne  lactometer,  the,  106 ; 
degrees  corresponding  to  scale  of 
N.  Y.  board  of  health  lactome- 
ter, 106,  261. 

Readings  of  cream  tests,  86 ;  of 
milk  tests,  35. 

Recknagel's  phenomenon,  107. 

Refractometer,  Wollny,  9 ;  immer- 
sion, use  of  for  detection  of 
watered  milk,  245. 

Reichert  number,  242. 

Reichert-Wollny  method,  241. 

Relative-value  tables,  209,  274. 

Rennet  tests,  140. 

Renovated  butter,  detection  of, 
242 ;  boiling  test,  242  ;  Water- 
house  test,  243. 

Reservoir  for  water  in  Babcock 
test,  70. 

Richmond's  milk  scale,  110. 

R8se-Gottlleb's  method,  5,  222. 


Salycalic  acid,  detection  of,  253. 

Salt,  estimation  in  butter,  239. 

Sampling  cheese,  97  ;  milk,  23,  20  ; 
milk  from  single  cows,  150. 

Sampling  tube,  for  cream,  181 ; 
McKay.  165  ;  Michels,  165  ;  Sco- 
vell,  163. 

Scales  for  weighing  cream,  80 ; 
milk,  150. 

Schmied  method,  the,  5. 

Scovell  sampling  tube,  163. 

Serum  solids,  10. 

Short's  test,  4. 

Siegfeld's  modification  of  Babcocs 
test,  71. 

Sinking  fund,  209. 

Separator  cream,  19. 

Skimming  of  milk,  detection  of, 
116. 

Skim  milk,  19  ;  Babcock  test  for, 
90;  chemical  analysis  of,  228; 
composition  of,  259;  condensed, 
256;  definition,  255;  sp.  gr., 
102  ;  test  bottles,  92. 

Solids  not  fat,  10 ;  formulas  for 
calculating  110;  tables  show- 
ing, corresponding  to  0-6  per 
cent,  fat  and  26-36  lactometer 
degrees,  264. 

Sour  milk,  sampling,  26  ;  analysis, 
228. 

Space  system,  the,  176. 

Specific  gravity,  102 ;  cylinders, 
103,  107  ;  influence  of  tempera- 
ture, 104 ;  of  butter  fat,  deter- 
mination of,  240  ;  of  butter  milk, 
229  ;  of  condensed  milk,  230 ;  of 
milk,  217 ;  of  milk  solids,  113  ; 
of  sour  milk,  229  ;  temperature 
correction  table,  262. 

Speed  required  for  complete  sepa- 
ration of  fat,  57  ;  ascertaining 
necessary  speed  in  Babcock 
test,  59. 

Spillman's  cylinder,  131. 

Standard  measure  for  calibrating 
test  bottles,  50. 

Standards  for  Babcock  glassware, 
258a. 


Index. 


297 


Standards  of  purity,  Government 
for  milk  and  its  products,  255. 

Starch  in  cream,  250. 

Steam  turbine  testers,  61. 

Stokes'  acidity  pellets,  125. 

Storch's  test,  248. 

Sulfuric  acid,  64 ;  table  showing 
strength  of,  67  ;  testing  strength 
of,  65. 

Sweetened  condensed  milk,  Bab- 
cock  test  for,  99. 

Swedish  acid  bottle,  47. 

Swedish  acid  tester,  67. 

Tank  for  cleaning  test  bottles,  43. 

Temperature  of  turbine  testers, 
36 ;  of  fat  when  tests  are  read, 
86 ;  of  milk,  influence  on  tests, 
152. 

Test  bottles,  30,  38 ;  apparatus 
for  cleaning.  41.  44  ;  calibration, 
48  ;  cleaning,  41 ;  cream,  79  ; 
draining-rack  for,  42  ;  marking, 
39 ;  skim  milk,  92 ;  rack  for  use 
in  creameries  and  cheese  facto- 
ries, 166  ;  tank  for  cleaning,  43. 

Testers,  54  ;  ascertaining  speed  of, 
58;  electrical,  63;  hand,  60; 
power,  61. 

Testing  cows,  number  of  tests  re- 
quired during  a  period  of  lacta- 
tion, 147. 

Testing  milk  and  its  products,  1 ; 
on  the  farm,  142. 

Test  sample,  size  of,  153. 

Tests  of  cows,  official,  150. 

Thermometer  scales,  comparison 
of,  283. 

ThSrner's  method,  5. 

Total  solids  in  milk,  10;  determi- 
nation, 221. 

Trowbridge  method  of  calibration, 
49. 

Turbine  testers,  61  ;  hot,  errors  in. 


Volatile  acids  in  butter  fat,  de- 
termination, 241. 

Wagner  skim  milk  bottle,  94. 

Waste  acid  Jar,  40. 

Water,  calibration  with,  48 ;  deter- 
mination of,  in  butter,  231,  233  ; 
in  cheese,  243;  in  milk,  220; 
reservoir  for,  70 ;  to  be  used  in 
the  Babcock  test,  69. 

Waterhouse  test,  243. 

Watering  of  milk,  detection  of, 
116  ;  watering  and  skimming,  de- 
tection of,  117. 

Weights  and  measures,  comparison 
of  metric  and  customary,  285. 

Westphal  balance,  219. 

Whey,  22;  Babcock  test  for,  94; 
chemical  analysis,  228  ;  composi- 
tion, 259;  definition,  258. 

Winton  cream  bottle,  the,  79. 

Wisconsin  creamery  butter,  sum- 
mary of  analyses,  189. 

Wisconsin  curd  test,  the  improved, 
137. 

Wisconsin  high-pressure  oven  test, 
for  water  in  butter,  237. 

Wisconsin  sediment  test,  251. 

Wollny  refractometer,  9. 

World's  Fair  breed  tests,  compo- 
sition of  butter  from,  188  ;  vari- 
ation in  quality  of  milk,  153. 

Yield  of  butter,  calculation  of, 
187,  and  butter  fat  test,  187; 
from  different  grades  of  milk, 
192 ;  table  showing,  from  1  to 
10,000  Ibs.  of  milk,  testing  3  to 
5.3  per  cent.,  279. 

Yield  of  cheese,  calculation  of, 
199 ;  relation  between,  and  qual- 
ity of  milk,  200 ;  table  showing, 
corresponding  to  2.5  to  6  per 
cent,  of  fat,  with  lactometer 
readings  of  26  to  36,  282. 


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Cream-Weighing  Scale 

For  Use  in  Connection  with  the  Bahcock  Test 

•"THIS  SCALE  is  especially  designed  for 
very  accurate  weighing  of  cream, 
butter  and  cheese.  All  bearings  are 
a§ate;  plates  are  porcelain;  base  and 
underconnections  are  galvanized,  mak- 
ing a  rust-proof  scale.  It  has  a  slide 
bar  in  front  to  balance  the  test  bottle 
and  is  provided  with  the  necessary 
weights.  Base  of  scale  10'i  in.  long; 
porcelain  plates  3  in.  square.  PRICE  $14.50 


Manufactured  by  HENRY  TROEMNER,  911  Arch  St.  PHILADELPHIA..PA. 


CHR.  HANSEN'S  LABORATORY,  INC., 

Little  Falls,  New  York 

Headquarters   for   coagulants   for  milk  in  Cheese  Mak- 
ing, Rennet  Extract,   R-P  Extract   and  Pepsin   Extract 

Rennet  Tablets  and  Cheese  Color  Tablets;  Liquid  Butter  and 
Cheese  Color;  Lactic  Ferment  Culture  and  Bulgarian  Milk  Culture. 
Also  Junket  Tablets  and  Nesnah  Desserts,  Buttermilk  Tablets, 
Pure  Food  Colors,  etc. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 

Los  Angeles 
This  book  is  DUE  on  the  last  date  stamped  below. 


Form  L9-Series  444 


SOUTHERN  REGIONAL  LIBRARY  FACILITY 


